If all of these animals are active at once, and can all act freely, this is a massive change to the balance of the class.
Due to the benefits of Companion's Bond, a Revised Ranger's animal companion remains competitive in terms of health, AC, and to-hit chance with player character classes, and eventually surpasses them in terms of single-attack damage (because you add your Proficiency Bonus to their +damage modifier).
In essence, you can consider an Attack from an Animal Companion to be roughly analogous to the Ranger making an extra attack, unenhanced by magic...but doing a little more raw damage on hit (before you consider other Ranger's features or spells).
Where this gets well and truly insane is when you pair this with Coordinated Attack (5th level) and Storm of Claws and Fangs (11th level).
For this example, let's consider a Ranger who took nothing but Wolves.
For a 5th level Ranger with this feature, they would have two animal companions. Each companion would attack on their turn, then each would attack again on the Ranger's turn. If the Ranger fights with a bow, this is already as if the Ranger is making 5 attacks per round (6, if dual-wielding instead), with each attack doing roughly equivalent damage to someone with a d8 weapon...considering the boost their damage rolls get from Companion's Bond, balanced by the fact that their stats are slightly lower, so they don't hit quite as often. A bit harder if you keep them close to another melee fighter so the wolves can use Pack Tactics.
Once this progresses up to Level 11, the Ranger now has 3 Companions and is generally making 7 or 8 attacks per round...and now three of those attacks are 5' area AOEs, and with that +4 proficiency boost to their damage, they are now hitting about as hard as someone with a good 2-Handed weapon.
Additionally, if you are increasing AC as their Dex score goes up, by level 12 the Ranger has 3 Wolves with an AC of 20, 65hp, proficiency on every saving throw, and Advantage on every saving throw.
In short, by level 12....you have a character who attacks as often as a max-level Fighter burning Action Surge, most of those attacks hit like a combatant with a 2-hander, and has 195 hp worth of disposable meat shields, with excellent defenses that they can throw into the fray whenever they want (you can rez your animal companion for the pittance of 25gp).
The Revised Beast Master is already a very potent build...giving them multiple Companions would make them devastatingly powerful.