Board Thread:General Discussion/@comment-26973802-20140905075301/@comment-32856285-20140907055358

The reason behind Mephisto and Iblis' possible idea of survival is merely that of a multiverse theory. Since they are beings of time and space, Mephisto can very well hop from one alternate timeline to another; universe to universe. This is plausible as it would explain how he would be able to summon a whole army of Mephistos, they are all him from alternate timelines.

So, it's not exactly about whether they are alive or not; it is more about whether we'll see them again in a different form or not. As while they may have died in the main Sonic Universe, despite the reset, they could have survived in a parellel universe (Sonic Boom for example).

If you ask why he hasn't tried again in destroying the universe, it is possible that there are alternate timelines where Mephisto reformed or was never evil in the first place and currently battle the evil versions of Mephisto. This can be the same with Iblis.

Personally, I consider that battle with Solaris as being held in a pocket dimension rather than the actual destruction of the timestream because as in a realistic sense and even a widely accepted sense: that would be impossible as there are so many timelines and universes, universes such as the Archie comic series, that would have to be involved in such a battle. Meaning we would/should have seen a whole army of superpowered hedgehogs for that final boss but we DIDN'T see any.