They don't need to reprint the book, just issue errata. And yes it's worth errata or else the claim of backwards compatibility will be blatantly false. Who chooses the 8th level Elven Accuracy when they can grab it at 4th level by default? The entire feat-level system will be wonky if they don't update prior feats to match that system and proclaim they're all open at any level other than 4th.
Who says an 8th level Elven Accuracy even exists? This is where you seem to consistently jumping to conclusions. You keep assuming old feats that will be taken from those supplments will be 8th or 12th level, but if they aren't... then there is no need to change anything.
All of the feats which people consider "broken" and might be moved to 8th level are found in the PHB. The feats in Xanathars and Tasha's (the only two books with a significant number of feats) all look like they'd be fine as 4th level feats. So, instead of assuming we will be breaking the game by taking a 12th level "Flames of Phlegethos" feat at 4th level, why not just look at the 1st level feats, and withhold judgement on 4th level and higher feats until we get that playtest document?
And, to cover this as well, saying that the game cannot be backwards compatible if the 2014 PHB lets you take the 8th level GWM feat at 4th level is missing the mark. Things that are rewritten in the 2024 PHB are clearly going to be meant to be rewritten rules, not interchangeable rules pieces, because if that was allowed, then there are a million broken combos, but it is clearly not allowed.
As for claiming my arguments have no merit because...I don't know you just hand waived them? That's a dismissive response. I didn't say they have to reprint anything, and we seem to differ on what is a "legitimate concern." I've seen entire characters based on what you appear to be dismissing as minor.
I imagined that by "updated or errata'd" you were talking about reprints. If you just mean they will need to release like a single page digital PDF explaining how to integrate things, that is far different and far easier than you've been making this sound.
But as for dismissing your concerns?
1) "I can't make an 18 stat human anymore." -> Yeah, I'm dismissing this. Rules changed. We knew that and it doesn't seem to be worth declaring the playtest broken and impossible just because some of the rules changed. At that point, you can't have a playtest. You don't need to playtest rules that never change.
2) Critical hits -> I've agreed with you. If nothing changes between this document and 2024, then this is a legitimate concern. A minor concern, since there are only three or four ways to cancel crits anyways, but a real concern I plan on bringing up alongside my other comments on the critical hit rules. Not dismissing
3) Grappling -> Another real concern, though one we have agreed is a rather easy fix. A single line in the new PHB on grappling and interactions with advantage on strength checks, and we are good to go.
4) Changes to abilities no longer recharging on a short rest -> Dismissed, because it isn't a real concern. This has been the case for Tasha's, for Fizban's, for Monsters of the Multiverse. This has been a shift for a long time. If your concern is actually that, say, 2024 Warlocks are going to work differently than 2014 warlocks, we return to #1. Rules changes are not problems that need errata'd.
5) All feats need to be given levels -> Dismissed because they really don't. If people are allowed to take feats that they have the pre-requisites for by level 4, then you can still take those feats. The only concern would come
IF they
DID update or errata the old feats to give them levels. Once they do that, you have rewritten the rules for those feats, and you will need to account for that. But if you don't, then they can just get them at level 4 like normal.
So, I am dismissing some of your concerns, but not out of hand. I'm dismissing them because you seem to equate the rules being altered to being some sort of problem, but all of the knock-on effects for other feats and short rest recharges and human limits are all not actually rules problems, they are rules changes. Meanwhile, Grappling and Criticals are actual rules problems that need addressed.