Verizon released a statement clarifying their policy change today; you can keep the unlimited data plan if you buy a phone off contract, subsidized phones require a new contract as always which means no unlimited data option.
I would be surprised if Verizon doesn't follow AT&T's lead by throttling the highest data users once the unlimited plans are officially dropped with subsidized phones. At which point the unlimited plans become meaningless...AT&T begins throttling at 2GB, buying the 3GB or 5GB plan is then a better deal as you can actually use more than on the unlimited plan. Of course that's just pure speculation, but the two major carriers do have a history of following each others' policy changes.