That's one way of interpreting a repost on a blog of something some woman at VZW supposedly told someone after he learned of some leaked data that has yet to be officially confirmed. It also goes against what others have said, and even so, I haven't heard anything saying that you'll be able to upgrade at 2-year pricing and keep unlimited, just that you
may be able to buy something full retail and run it on an existing unlimited 3g plan. Even that isn't confirmed though, and I certainly wouldn't count on what she said.
Again, if you want to make sure you get locked into unlimited LTE for the forseeable future, your best bet is to grab a Charge now (or T-Bolt or Rev if you hate battery life

). A few things here and there seem to suggest that you may have other options, but its not likely and the majority of what we've heard suggests that you will only be grandfathered with your current plan. They may allow you to upgrade at 2-year pricing and keep unlimited, to get people to re-sign, but most likely you'll just have to go full retail. Even if they do allow it, which is unlikely, I don't expect you'd be able to switch from 3g to 4g.
None of this info has actually been confirmed, which means the plans may not yet be completely finalized, or possibly this info is incorrect (though not likely). Still, it may be correct at this time when it leaked, but may change before it becomes "official". We here in the Bionic forum are certainly no strangers to that. So if you wait you may find out there's a way to keep waiting, but we haven't heard anything reliable to suggest that's the case, and it honestly wouldn't make much sense if they truly are as committed to this tiered thing as they claim. So wait if you want to, but the safe call at this point would be to grab an LTE phone and unlimited data with your upgrade while you still can.