I seriously doubt they would ban you from service without so much as a warning.
So many things have pages of fine print.
I have not read the entire contract I have with Verizon.
If rooting your phone violates your warranty and if that means they don't have to assist you anymore, then you already have been warned. If tethering violates the term of your contract then, again, you already have been warned. That being said, if someone wants to post those relevant terms of the contract and share with us all, please do so.
Not that I advocate excessive tethering or anything, but with the current apps, VZW has no idea if the 15gb I downloaded last month stayed on my phone, or was forwarded via WiFi Tether to a PC....
It's just like how Bright House cable cant tell (easily) which PC on my network gets the most use, as far as they know, it's all going to and from my router.
It depends. If you tether and visit some webpages when your internet is down they most likely can't tell.
If you tether, visit Hulu and stream down some shows they can tell. Your phone can't generate that traffic and can not use that traffic.
If you tether your xbox and play some games your phone also can not generate nor use that traffic. ISP's most definitely can track the type of traffic and the protocols used.
Now, that being said nobody knows if they will do anything. However if it is impacting their traffic and they terminate the contracts for the first 50 people they catch tethering I bet it alters the behavior of a bunch of other people who are doing the same.
Odds are you won't be the one caught so we can all sit back and keep an eye out on things and either some random people get nailed, or they don't. Then we each decide what we want to do in the future.