This is the first time devs abandoning the game actually gives me positive vibes. Finally I can complete the game without being afraid whether or not my save/story will be corrupted by new versions. Also I don't think there needs to be upkeep or whatnot as the game is as sandboxy as it can be. But ofc, if they ever come back to improve it, why not.
As for 7DTD ending the same way, why not? I mean, PE got abandoned after it got officially released (with some minor patches after release as well). Maybe you're used to this huge turbulence, content adding/changing etc. we have in 7DTD now, but remember that this is alpha, and stuff like this is typical for alphas. Then comes the beta with optimizations and small tweaks, and then comes the actual release, which will be pretty much set in stone and everything will be added/modified onto the stone base. Abandoning the game after release is not a normal or good practice, but it is completely normal and natural that the development speed and dynamics decrease, often to the point when you don't even know if someone is working on the game or not.
As for me, in the age of early access, alphas, betas etc. I'm very grateful when the developers actually make it to the 1.0 even if they abandon it right after. A promise is a promise, and I take it as fulfilled if the game releases fully. The only bad abandonment for me is when developers just leave the game in alpha/beta/EA, that is the true crime.