It's hard to say on the fuel tank size, but if it incorporates those side panels as it looks to I would imagine you could in fact create a pretty decent size tank. Not 30 litres, but I would have thought 20 might be possible and that would be plenty for the vast majority of people.

The rear end is going to need some thought though. That current design, with the silencer fully on the outside of the swing arm, is going to leave the silencer very vulnerable to damage when the bike is dropped and looks like it will be a problem for luggage, especially soft bags without frames. I think they'll need to find a way to tuck that in and also ensure the sub frame is up to the job for luggage etc. But apart from that, I quite like it.