Well, It's been kind of obvious for awhile that VZW will phase out unlimited data...there's no real profit in it for them. They've already stopped new customers from getting it (last year), only allowing "grandfathered" clients to hold on to it. Now (June 28), they've stopped grandfathered, subsidized clients from doing it. Right now, no one can BUY an unlimited plan, they can only renew it by paying full retail price for a new phone, meaning the CLIENT is subsidizing unlimited data!
So, unlimited data will stay profitable for VZW for awhile, since the client is paying for it. But sure, at some point in the future, they can simply say, "Well, unlimited data is proving to be a huge drain on our resources and thus a drain on our ability to service our customers, so as of August 1, 2014 (or 2013, or even 2012), we will automatically convert users of unlimited data to a 4 GB plan, at a reduced rate (or not)...blah blah.
They can do this at any time, so let's just enjoy UD while we've got it. I've never expected to keep UD indefinitely. Someday, it's going to go away, and you can cuss and threaten to leave Verizon and go to Change.org all you want...but consider this: How many times has Verizon changed ANYTHING because of customer protest? Not a long list, I'll bet.