The only reason the TB is having problems with ICS is due to the fact that ICS is such a drastic change to the RIL and developers can't crack it. With an official 4.0.x RIL we will be able to get custom ICS ROMS working just fine I expect. And based upon the earlier replies, Jelly Bean doesn't have any significant changes to the way it handles the radio, so it should be feasibly possible to jump to JB as well, once we get some kind of leak/update from Verizon.