If you sign up for a two-year plan, you will still be required to meet your contractual obligations.
However, under this policy, you could bring your iPhone to Verizon, and it would work.
You can’t use an iPhone on Verizon. Verizon is a CDMA network and the iPhone is a GSM phone. The two systems are technically incompatible.
IMHO, this is nothing but a publicity move. Verizon will have to program any device to use their network and they will almost certainly charge a sufficient fee to discourage people from bringing their own phones.