Retraining feats?

While I was reading through various D&D 3.5 splatbooks, I found a way to retrain feats.
Upon level up, the character is able to switch out a previously attained feat for another that they meet the prerequisites for.
This can only occur at every third level up or upon attaining a bonus feat (fighter, monk, wizard etc). This allows attainment of one feat and the switching out of another.

I'm yet to find a similar effect in Pathfinder. Any thoughts as to the viability of this?

It depends on the feat whether I'd allow it or not. Passive bonuses such as Iron Will cannot be (usually). Things implying that you've learnt a skill, such as a weapon proficiency or item crafting cannot be. If the feat is a prerequisite for other feats you have then you cannot swap it out. And of course, no swapping feats for things that you couldn't qualify for earlier (No swapping out Stealthy you picked at level 1 for Bleeding Critical).

However, if there is some pretty good reason in game why there's no point to it anymore (Such as an archer going permanently blind), I would allow mass retraining, assuming you didn't just retire the character.

In other words, you can swap, based on GM approval. As usual. If the swap makes sense or is otherwise realistic, then you'll probably be allowed to swap.

The majority of its use seems to be in wizards that are optimizing, such as where one takes brew potion and later switches it out for a metamagic feat.
I reckon that switching weapon related feats are not really a hassle (obviously you can't switch out class or race weapon proficiency).

I agree though that Iron Will should be permanent, whirlwind attack should not and cleave/great cleave should be open to switching if the character ceases to use a slashing weapon.