We probably won't find out what is what until the official announcement for HTC Thunderbolt. Of which it seems most official announcements only come one or two days before the phone is available.
Most likely you will hear about it when a user posts the link in this other thread.
Thanks Ann! I finally got a pair of employees in the Loyalty Department to talk a little (its obviously their policy isn't to talk about pricing of any kind of items or services not yet available). Both of the employees were very nice and helpful, and both said I would not be charged additionaly to upgrade any and all of the lines on my phone to 4G phones and using the 4G network.
It took me a while and several attempts before I could get anyone to talk, but this is good to know. Certainly do not take my word for it, I am simply a newbie who came looking for an answer. And even if the two employees were telling me the truth, who knows if that will be the case in a couple months? If it ends up being true, I may have to make the jump to 4G afterall (when it comes to my area, that is.)
Just be reluctant to believe what they are saying. The CEO has already announced 4G (LTE) data will be billed differently. I am banking on grandfathering of 3G data plans will occur.
However, the only thing that makes me doubt that initially is, Voice will still be over 3G for the initial phones coming out. THAT may allow the grandfathering short term.
I think VZW is going at the correctly... Aircards, Phones with data not voice on 4G, then the combo.