Pixel 1 is unique in that they forgot to put a deadline into the deal. They didn't make the same mistake for the next ones. And, yes, unlimited original quality still works for me as of today, but I'm not taking any chances with deleting my local copies.
Though, to be honest, Pixel 1 is absolutely horrendous when it comes to replacing the battery. Even if you did manage to open it without breaking the screen, good luck putting it back together. I did a poor job on mine, part of the bottom bezel didn't stick and there are weird green glitches on the screen when you press on that part. This thing really wasn't designed to ever come apart.
So, anyway, I have a Pixel 4a on its way to me, and I'm paying 50€/month for a server with much more disk space than I know what to do with. Are there any decent self-hosted replacements for Google Photos?