On the plus side, planeswalkers dying of old age means they could just get rid of the damn Gatewatch and some of their other entangled retcons by skipping the next hundred years or so. Well, Nissa would still be alive, but I'm sure Ob Nixilis could take care of that. Not that that's going to happen, but a man can dream.

And yes, they have to adopt a proper timeline again. It's not like there isn't a bunch of knowledgeable fans out there who invested (and are still investing) a lot of time and energy into figuring this stuff out.