They've been farming the Cuba thing since the boomers were children. Every election there are bitter Floridian descendants of Cuban exiles to court. It would be insane for them to permanently resolve the issue, and any actual resolution would inevitably be a disappointment to them.

“Winning” in Cuba would also be very difficult. Sure Venezuela looked cool but what really changed?

Exactly. Cuba is a pain in the US politics since generations now. If Trump would solve it, that would boost him. But if it fails, with declared victory but significant partisan warfare afterwards - not so much.