Apropos of nothing more than my idle speculation, I’d guess they will return to the transport tycoon genre if they are able to do so. Before Skylines took the crown from SimCity as the preeminent example of the genre, they made the Cities in Motion games, which were narrowly focused on improving the mass transit of existing cities (as opposed to building the city itself). I know the second CiM game had some interaction between the city and your efforts as transportation czar (in the same way you could indirectly influence a citiy’s development in, say Railroad Tycoon), but the emphasis was always on transit. I imagine the newly independent team will want to keep their focus narrow, unless another publisher swoops in to replace the safety net.