... but only attack creatures you threatened initially

The effect of Adamantine Hurricane says:

You make two melee attacks against each adjacent opponent you threaten when you initiate this maneuver.

If initiate is to maneuvers as cast is to spells¹, then we needn't read this as the attacks occurring at the time of initiating. Compare and contrast the spell Whirling Blade (Spell Compendium p.238):

You hurl a weapon held at the time of casting, and it magically attacks all enemies along a line to the extent of the spell's range. You make a normal melee attack, just as if you were attacking with the weapon in melee, against each foe in the weapon's path ...

Emphasis mine. This explicitly shows that your standard action Whirling Blade spell is cast, and then you make some attacks with no additional action. Those are attacks are made by a weapon that is set at the time you cast. The attacks can't be made while you are still casting because you are not holding the weapon at that time, invalidating it for your selection of weapons to hurl.

By this analogy, and due to its text not being explicit either way, we can read Adamantine Hurricane's targets as being set when you initiate, but the attacks are made (rolled and resolved) as the effect afterwards. If you use Wolf Pack Tactics to move where you threaten a new opponent, you may not make an Adamantine Hurricane attack against them.

Further, if you move such that you no longer threaten an opponent that you did when you initiated Adamantine Hurricane, you will be unable to take the melee attacks that you were entitled to. This must be the case for any circumstance that puts them out of your reach or otherwise unable to attack them, as the impossibility of the action outweighs the fact that you were granted it.

¹ That is, both mean 'use' or 'expend'.

... and your targets change with each step.

Tome of Battle, pp.39-40, Resolving a Maneuver or Stance:

Actions during a Maneuver: The Initiation Action line of a maneuver description provides the action required to use that maneuver. For example, the initiation action of the radiant charge maneuver is 1 full-round action. Thus, as part of your full-round action, you bring about the effect in the maneuver description.

Tome of Battle, p.42, Maneuver and Stance Descriptions (Type): Strike:

Strikes almost always require a standard or full-round action to complete. Most of them involve a melee attack as part of completing the maneuver.

Tome of Battle, p.46, Duration: No Duration:

For example, a strike with an initiation action of 1 standard action would effectively have a duration of 1 standard action; the effect of the strike is tied to the action of making the attack.

These three pages all agree that the full effect described by a Maneuver, specifically including a Strike's melee attacks, are within the Initiation time. So while you attack your adjacent foes, you are still Initiating Adamantine Hurricane. This is important, but does not of itself mean your targets may change.

Targeting a Maneuver on p.45 says,

You might have to make some choice about whom your maneuver is to affect or where it will originate.

However, it does not say when you have to make this choice. I've found no text stating that a decision about targets or aiming when you choose a Maneuver to Initiate (the first step in Initiating it). Contrast with spells, where "you make all pertinent decisions about a spell (range, target, area, effect, version, and so forth) when the spell comes into effect" [PHB p.174].

As there is no general rules, the Maneuver's effect must guide us in when and how we choose our targets. The effect of Adamantine Hurricane says:

You make two melee attacks against each adjacent opponent you threaten when you initiate this maneuver.

As it happens, we make no choice for this one. All adjacent opponents threatened by our character are chosen as targets for us. If we move during Initiation, then that selection of targets changes - with clever use of Wolf Pack Tactics the number of "adjacent opponents you threaten when you initiate this maneuver" can be extended as far as your movement allows.

You can move after each attack...

Adamantine Hurricane has you make melee attacks. Wolf Pack Tactics allows you to move 5ft after every successful melee attack.

... but only attack creatures you threatened initially

The effect of Adamantine Hurricane says:

You make two melee attacks against each adjacent opponent you threaten when you initiate this maneuver.

If initiate is to maneuvers as cast is to spells, then we needn't read this as the attacks occurring at the time of initiating. Compare and contrast the spell Whirling Blade (Spell Compendium p.238):

You hurl a weapon held at the time of casting, and it magically attacks all enemies along a line to the extent of the spell's range. You make a normal melee attack, just as if you were attacking with the weapon in melee, against each foe in the weapon's path ...

Emphasis mine. This explicitly shows that your standard action Whirling Blade spell is cast, and then you make some attacks with no additional action. Those are attacks are made by a weapon that is set at the time you cast.

By this analogy, and due to its text not being explicit either way, we can read Adamantine Hurricane's targets as being set when you initiate, but the attacks are made (rolled and resolved) as the effect afterwards. If you use Wolf Pack Tactics to move where you threaten a new opponent, you may not make an Adamantine Hurricane attack against them.

Further, if you move such that you no longer threaten an opponent that you did when you initiated Adamantine Hurricane, you will be unable to take the melee attacks that you were entitled to. This must be the case for any circumstance that puts them out of your reach or otherwise unable to attack them, as the impossibility of the action outweighs the fact that you were granted it.

You can move after each attack...

Adamantine Hurricane has you make melee attacks. Wolf Pack Tactics allows you to move 5ft after every successful melee attack.

... but only attack creatures you threatened initially

The effect of Adamantine Hurricane says:

You make two melee attacks against each adjacent opponent you threaten when you initiate this maneuver.

If initiate is to maneuvers as cast is to spells¹, then we needn't read this as the attacks occurring at the time of initiating. Compare and contrast the spell Whirling Blade (Spell Compendium p.238):

You hurl a weapon held at the time of casting, and it magically attacks all enemies along a line to the extent of the spell's range. You make a normal melee attack, just as if you were attacking with the weapon in melee, against each foe in the weapon's path ...

Emphasis mine. This explicitly shows that your standard action Whirling Blade spell is cast, and then you make some attacks with no additional action. Those are attacks are made by a weapon that is set at the time you cast. The attacks can't be made while you are still casting because you are not holding the weapon at that time, invalidating it for your selection of weapons to hurl.

By this analogy, and due to its text not being explicit either way, we can read Adamantine Hurricane's targets as being set when you initiate, but the attacks are made (rolled and resolved) as the effect afterwards. If you use Wolf Pack Tactics to move where you threaten a new opponent, you may not make an Adamantine Hurricane attack against them.

Further, if you move such that you no longer threaten an opponent that you did when you initiated Adamantine Hurricane, you will be unable to take the melee attacks that you were entitled to. This must be the case for any circumstance that puts them out of your reach or otherwise unable to attack them, as the impossibility of the action outweighs the fact that you were granted it.

¹ That is, both mean 'use' or 'expend'.