It's a small economic quirk, but I imagine many Cubans would be selling their old American cars to collectors State-side for a quick cash influx.
And Americans would be eager to travel to Cuba for tropical tourism. That feels like a longer lasting economic change.
Of course there'd be a bubble market on Cuban cigars that would arise, climb, then settle as the demand declines as the idea of a Cuban cigar becomes more normalized.
I've heard Cuba has some novel treatments for lung cancer. I imagine there'd be a market for medical tourism that would emerge from that, as I sincerely doubt the FDA would evaluate and approve a foreign treatment created under a Communist government with any haste.