This really wasn't set in stone in TL1 and TL3.
I've thought about ressurection ending before, and probably already mentioned it here. What seems set in stone to me is that it will feature no Madoka. Because she's the only one to trigger that ending. If she learns that it is possible to bring everyone back AND make them humans again, then L himself would give 62% that Madoka may go for it. Then die along with WN - pretty much the sacrifice and the bitter ending we've been expecting. But this is likely to prove wrong next Thursday. Alas, the only thing I can bet on is that there will be no other loops. For obvious and painfully expectable reasons.