I have a human cleric with the Extend Spell feat thanks to the domain power of the Spell domain. The first level human bonus feat was spent on Persistent Spell and the regular first level feat was spent on DMM (persist). Now he's taken up one level of the Ordained Champion prestige class and I would like to swap his Spell domain power for the Power Attack fighter bonus feat. So he will lose the Extend Spell feat, which was a prerequisite for the Persistent Spell feat. Will this have any consequences according to the RAW? Which?
From the d20 SRD:
Some feats have prerequisites. Your character must have the indicated ability score, class feature, feat, skill, base attack bonus, or other quality designated in order to select or use that feat. A character can gain a feat at the same level at which he or she gains the prerequisite.
A character can’t use a feat if he or she has lost a prerequisite.
When you lose the prerequisites that qualify you for a feat, you also lose all benefits of that feat. You do not lose the feat itself, and when you meet the prerequisites again, you re-gain the benefits.
The cleric won't be able to use the feat Persistent Spell until the feat Extend Spell is regained
The feat Extend Spell is a prerequisite for the feat Persistent Spell (CAr 81), and, unless the cleric manages to acquire the ability to employ the feat Persistent Spell while ignoring prerequisites somehow, losing the feat Extend Spell means being unable to use the feat Persistent Spell (and, by extension, Divine Metamagic (Persistent Spell) (CD 80)). The feat Persistent Spell remains on the cleric's character sheet, but the feat's benefit can't be realized.
The Player's Handbook on Prerequisites says
Some feats have prerequisites. Your character must have the indicated ability score, class feature, feat, skill, base attack bonus, or other quality designated in order to select or use that feat....
A character can’t use a feat if he or she has lost a prerequisite. For example, if your character’s Strength drops below 13 because a ray of enfeeblement spell, he or she can’t use the Power Attack feat until the prerequisite is once again met. (87)
This makes swapping out prerequisites a bad idea generally. Note that the above differs slightly from the Player's Handbook's own later description of Prerequisites:
A minimum ability score, another feat or feats, a minimum base attack bonus, a minimum number of ranks in one or more skills, or a class level that a character must have in order to acquire this feat. (89)
However, most agree that the initial quotation is simply more complete, the latter quotation not contradicting the former.
It is important to note, in your "recursive Scenario", the wording of your feats.
If feat A is a prerequisite for B that is a prerequisite for C, and I have all three of them but then I lose A, will I still be able to use feat C? (since I still have B)
if you lose feat A, you cannot use feat B. but you can still use feat C.
If feat C is worded something like "While using feat B, you may...." then you cannot use feat C, as you need to use Feat B to access C.
(Example, Shock Trooper's heedless charge. assuming your strength goes under 13, you can no longer use power attack, but you do not loose shock trooper. However, heedless charge in shocktrooper states that you get the bonus if you "Make a power attack after you charge". Since you cant power attack, you cant heedless charge.)