um...wouldn't Secret Wars invalidate this theory?
If Cap changed the timeline during Brubaker's run he either changed the 616 timeline or outright created a new timeline...either of which would have been destroyed during the death of the multiverse leading up to Secret Wars.
I mean you can't really tie anything back to time travel pre-Secret Wars anymore can you? The 616 reality is already different than the new universe we have now.
Reverend Meteor (and this is why I hate stories about the multiverse and/or time paradoxes)
Secret Wars/Convergence/Crisis should indeed invalidate this theory and the Mephisto Mindwipe as well.
But marvel's plan to reboot their universe with Secret Bores was about as poorly thought out as DC's plan with Crisis on Infinite Earths and its aftermath.