There's still plenty of room for expansion of the crossing time / crossing dimensions ideas.
For example, the two have not been combined yet (at least not throughout the game).
I also would be interested in a game that was more flexible that CT or CC. For example, imagine a game like CT where you could visit at literally any time, instead of having 6 or 8 set points in time...it may not be feasible, but imagine the possibilities if it were. If a game like Spore is possible, surely this is too...