Brock can come and go at his own leisure. Would he go to TNA? They don't have enough money to pay Brock, unless they auction off pieces of Hulk Hogan or something. Japan? Possibly, though their style of wrestling might be too harmful to Liddle Bwocky. Just kidding, he's a pretty hard man but I'll say again, I'm not sure he could handle that these days.
So the way I see it - which is the way it is - is that now that Brock and Vince have a somewhat repaired business relationship, we'll be seeing more of Brock at some stage. I wouldn't bet on right away....but I wouldn't bet against it.