I know a lot of people like the concept of feat chains, but I have always hated them. It just felt like justification for a bad feat because it was a prereq for a good one, and it severely limits customization. I think this is an even bigger problem in 5e when feats are so limited, the vast majority of players (that play to about 8-11th level) will only ever get 3 feats for a character (4 for a human), and that's assuming no ability score boosts. So even a single feat chain basically dictates your characters' entire feat choice.
I think feat levels are a far superior option. You can make penultimate feats that require level 8, and then the player can decide how to get there. If they want to make a chain of similar feats to be the ultimate in X, fine. If they want the cool 8th level feat but also do some other stuff, fine. It also removes the imbalance that humans can bring into the mix, where the right chain means that humans get a major power boost over the competitive.
So I think that with the arrival of feat levels, feat chains are obsolete. The levels are simply a superior mechanic....as long as they are used well. I think the vast majority of feats should be level 1 or 4....with only a handful of "truly powerful ones" being 8th....even 12th feels a bit too long for most feats to come online.
Thoughts?