I think that much was pretty obvious from his speech with Capone when he hands over the operation saying "you've won". Although, possible spoilers for next seasons:
He does come back to America to set up another gang with Luciano, Lanksy and a few others but I don't think they'll bother in the show.
And yeah, you're probably right that they won't bother.
Plus, he didn't return until three years later anyway, and there's no guarantee the show will progress that far (although I hope it does).