He can definitely test the pro waters. He's shown a lot and shown that he has even more upside, imo. He can gain weight while getting paid and any pro team will get him extended for a short jumper more so than SU. Maybe he doesn't even care about the NBA versus playing overseas, I dunno.
I think he'll be back, but the reasons if he wants to try going pro or elsewhere? He is fifth out of the five starters in FGA/game. And not by a little, by a lot. JGIII is fourth out of the five starters at 10 FGA/game and Jesse is at 6.9 FGA/game. That is while being one of the top FG% in the country and hilariously having to cover for the ineptitude on defense that surrounds him.
Again, I think he's coming back, but I can see a world where he may want a change of scenery.