this isnt going to happen for a few reasons, verizon isnt a gsm network, apple would have the re design the phone from scratch in terms of the network.
most of the world uses gsm, would make it easier for apple to have version of the phone
verizon wouldnt let apple use there own OS, one reason apple went to ATT.
and because ATT has an exclusive contract for 5 years, and even when its over, apple has the option to resign which im pretty sure they will considering how well its doing with ATT, and i doubt they would ever go with sprint (the next worthwhile gsm network)