IMO, expanding the field will make for some more interesting games among the lesser teams that don't really have a big separation between them. Different styles of play, different conferences etc. I think that part will be like Bowl games used to be when you'd have some really cool match ups.
The part that won't change is that the same 2-3 teams keep being the same 2-3 teams at the top of the recruiting rankings every year, then there is going to be a big gap between them and the rest of the field.
The theory the expansion folks put forth is that ultra elite kids see lower teams in CFP, kids want to be in CFP, maybe elite kid goes to "lesser" school now. What that theory doesn't account for is the kids wanting to get to the NFL more than just be in the CFP. A handful of schools are known NFL factories. As time has gone on, those teams are like a college version of IMG. The best of the best go there to get a jump start on getting to the next level.
I don't know for sure but I don't think playoff expansion will dilute the concentration of elite talent at the top 2-3 schools. NIL might, but expanded playoffs won't imo.