No one can say with a hundred percent certainty what will happen when tiered data hits. Even VZW employees probably won't know the specifics until that week. VZW likes us to be in the dark.
(from Beka's DX)
Actually you can. So long as you are in an unlimited plan when VZW turns to a tiered plan system you will stay in an unlimited plan. HOWEVER you will not be able to get any subsidized phones or make edits to your plan from then on out as that woudl constitute a plan change and thus change your plan into one with tiered data...
Theoretically, yes. Hopefully this is the case! But if VZW has proven anything over the past several months, it's "We do what we want, when we want it, and how we want it." I don't put anything past them anymore.
You are in a contract and as such they legally can not change your payment terms. They can change some other items such as incentives, subsidies, and such but can not change your pricing...