Once the deal was done, they could shaft you. The only thing you could do was keep ownership and grant technical administration over to the new domain user for a year. Would they want that?
Well, if I knew the domain holder personally, fine for them to keep the reins, but if I didn't, I prob wouldn't/couldn't take the getting-held-to-ransom risk if things took off. I don't have investors, but I bet people who do would say the same thing, only more emphatically
I agree with you, but the amusing thing is that all of these problems could be solved with a simple contract. Lease with option to buy at set price, or guarantee to sell unless breached, etc.
Its probably a 1 page contract, even. The real issue is trying to enforce it if someone defaults on that contract - it could get impossible/expensive if they are out of the country.