If they do a split cour, ending episode 12/13 with Owl's appearance would be the biggest troll move I can think of. On the other hand, the second cour would start with Owl and end with Owl.
I once read on 2ch that the booklet some people got with volume 12 contains hints that they intend to animate the Kanou lab arc. I don't know what kind of hints the booklet contained exactly. But it's a slight hope that they want to do a split cour.
Edit: OK, it's the second greatest troll move. The greatest troll move would be stopping with Kaneki sitting in the torture chair.
Okay, that actually worries me. I figured they'd rush to the currently scanlated chapters, but it didn't occur to me they might rush past them.
I guess I could avoid watching anything the scanlations haven't covered, but I'm sure the other readers will let me know what happened.
Damn it, Pierrot, hold your horses.