If they wanted to, Verizon could slowly introduce the idea to consumers by dropping traditional subsidies and lowering monthly rates, but allowing people to buy phones at a "subsidized" price by spreading the cost of the phone subsidy (+ a fee, of course ) over the life of the contract. Even then, those people who get a subsidy could save if they held onto their phone beyond 2 years.
Dropping subsidies also would force manufacturers to compete on price more, hopefully pushing retail prices down a little. And it would possibly hurt Apple, since Apple could no longer push carriers to subsidize the iPhone to make it competitive with Android offerings; Apple would have to eat the difference to keep price equality (which they won't, since Apple doesn't often compete on price). For instance, VZW charges $599 for a full price GS3, but $649 for a iPhone 5. Both are available subsidized for $199.
It's a big win for consumers regardless, though, assuming VZW does drop their service rates along with the subsidies. Let's hope it happens!
(One possible additional motivation for VZW: with no-subsidy cheaper plans: the old $30/mo unlimited plan may be less appealing to all but the heaviest data users since theoretically metered data will be cheaper without subsidies. We all know that VZW is looking for ways to get people to drop their unlimited plans.)
I like the idea of buying at full price as well, but I think they should have an option like T-mobile's interest free financing for those that can't afford the full cost. At the very least, I think plan prices should be reduced at the end of the contract by the monthly subsidy amount since the phone is now paid off.
I like having options, so I would be ok with offerings if subsidized and unsubsidized plans, where the customer can see a side by side comparison of the prices to make a more informed decision.