me and my partner were late
That says it all. The sizzle is gone.
Its like baseball cards - the time to sell a Mark McGwire rookie card was when he broke the record, a rookie card fetching minimally $450 bucks, they were in demand, and there was a large market for it. Now you would be lucky to get a buyer at $1.00 per card.
If you wait too long the appeal, the newness, novelty, and "must have" is gone.
Aside from any possible TM or copyright issues, you missed the boat on this.
Irregardless what the sequel will be called, it is not going to be TheHangover.