Well, the trailer did give a rather unsubtle hint. Unless the guy speaking is an imposter pretending to be him, I'd say it's pretty likely.
- Word of God says unambiguously no, at least beyond In Name Only. The quote was just a nod to the old games: X isn't allowed to take place anywhere but Ashan, and that entails certain limitations — among them the fact that Ashan is pure fantasy, without any science fiction elements.
- Utterly jossed with the release of the game — the Big Bad is a native Ashan entity. Sheltem's only appearance is a number of mentions as 'the Usurper' in a series of books that retells the plots of the previous Might & Magic games in somewhat veiled and poetic forms.