The other day I saw a post on tublr about how Simon "Wonder Man" explained, in a  mock, Simpson-like video, what a reality-altering event was, and Miles Morales asked him if there was anything to prevent them.
(The Answer? No, obviously).
So, it came to mind the time when, a couple of years ago, in Battle of the Atom, Young Original X-Men Scott Summers got injured deadly (but got better because, obviously, the team happened to just have an Omega Level Healer on the inside. Obviously.), for, like, two panels, and in those two panels Adult Scott Summers ceased to exist (as in, he vanished and for a few panels people didn't understand or remembered he was supposed to be there), just to reapper when Young Scott got better (again, healer.).
That would mean that Young Scott and Adult Scott are one and the same, right?
Wrong.
( Spoilers for X-Men Blue )
So, seriously, a retcon in two months???