Apparently, now is the time to upgrade your Verizon phone if you want to keep your grandfathered unlimited data plan in tact. According to tips we've received, along with reports from Droid-Life and Android Central, the aforementioned type of users are not being forced into a tiered Max data plan during the upgrade process. There doesn't seem to be any bit of trickery required to make it happen either -- folks just go through usual upgrade motions to get a brand new phone on subsidy, and come out with an order confirmation that has all-you-can-eat data still onboard (see above). We've reached out to Verizon to find out whether this is an issue with its website or a shift in policy, and will post an update if we hear more. Let us know your results if you're brave enough to try it out.
[Thanks to Minji and everyone who sent this in.]