I've said this before, I'll say again: I dream of a ZUN+Cave (or some other company such as Treasure) collaboration featuring Touhou characters on arcade (more like a spinoff, to not affect canon that much, or even another episode, if it's not going to be too much troublesome for ZUN to think of it). That would be awesome! (as long as the game still features silly, non-lethal fights)
ZUN's characters, setting and style, with Cave's patterns (this one would have ZUN's collaboration), bgms (same here), difficulty, pacing (think of stage portions), scoring system... TLBs... what can be more awesome than this? A future Seihou+Cave? :p