I realize my post above (#37) diverged a bit from what the OP is asking, but I think it is relevant. But to take one element from that, and to respond more directly to the OP, I think a lot depends upon how the "Stranger Babies" respond to this change. The old-timers who are still around have gone through this before, some several times. But what we don't know is how the new player base will respond to changes in a game that, for them, has not yet changed.
And of course a lot of their response depends upon how much the game changes, and in what ways. But I think WotC is very aware of this, and will try bring the game only up to the edge of what they think won't rock the boat too much.
Another fact that seems barely mentioned, but I think is huge: 5E is quite different from past editions in that there are minimal splats. Most of what is published are adventures and settings, and those sorts of products are more "update resistant" than splats. We've already seen WotC's planned approach: they folded two older splats (Volo's and Mordenkainen's) into one new book. Presumably they'll incorporate two more, Xanathar's and Tasha's, into the 50th anniversary PHB.
Meaning, they aren't going to have to re-publish everything - just the core rules, and then move on from there. They could even do a 5.5 and the uproar will be (or should be) less than in past editions, because there is less to update, and most of it can be updated within the core rulebooks.
So my prediction is that it will be more seamless a transition to the 50th anniversary because of the nature of the 5E product line: heavy on adventures and settings, relatively light on splats.