Some people have postulated that Verizon doesn't want to release the i760 now, to avoid people returning the phone during the trial period to buy an iPhone. Does Verizon really gain anything by doing that, though?

If somebody is willing to try the i760 it means they're at least considering switching to/staying with Verizon. If they like it not only has Verizon made a phone sale they have a valuable customer for the next 1-2 years. Without attractive phone options even more people are going to switch, and given the fact Verizon makes most of their money on service contracts that seems like a bad move.