Want a 750 twin? Look no further:A 1000cc parallel twin? Highly unlikely. It would have to be a new engine. I'm not that familiar with the engine but doubt it has room to go up to even a 750. Which by the way is the strangely absent displacement in the world, sadly. Except for the GSXR.
It was an odd twist of fate that the 750 class died. Overall it might be the best size for most every application using modern design. I'd say Kawi missed the boat by making a new 650, not a 750. The result is fine in the Versys. The Ninja not so much. Just not enough grunt low or power high to make many really happy. 650 is right for the overall Versys design I suppose but power sells.