In BW Ash has caught some Pokémon in a row, so it wouldn't be too Farfetch'd for him to get another one so soon.
However, by looking at the previews, it doesn't seem that there will be a capture, especially after seeing that the old Stoutland is still around, and I seriously doubt that Litten would just leave him behind without an extremely good reason.
Perhaps Stoutland could stay with Kukui, becoming the new Pokémon the professor looks after since Rockruff went to Ash. It would allow Litten to both be with Ash as well as be able to keep watch on Stoutland when Kukui isn't around or is teaching class.