It may very well be that LTE will mark the point that carriers utilize different SIM cards as a new form of subsidy lock. So, while everyone claims that their network is “open” a device maker would still have to release different versions of each device, that makes it compatible with each network’s SIM card.

With WiMAX, support seems to be around the concept of using MEIDs to classify devices. That still requires the carrier to activate a foreign device, but does not require a specific carrier SIM be inserted.

In addition, it is not clear if LTE will support a “uSIM” that would be carrier-independent. If so, it would be possible that carriers would offer a “SIM for unlocked devices” thus enabling device manufacturers to ship unbranded phones. A customer would simply need to trade in their AT&T or Verizon SIM for a AT&T or Verizon uSIM… and then insert that into an unbranded phone.

All this appears to revolve around carrier interest in keeping the subsidy model alive, in light of the FCC’s intention to force carrier to take their phones from one network to the next, after their contract expires (or, when they pay the early termination fee).

On that radio class- will the 7.2 HSPA devices work on LTE? If so, then I could use an unlocked AT&T Tilt (I think it can do 7.2 HSPA) on Verizon as soon as next year?

Wow, there is not going to be much of a reason to go with AT&T once Verizon starts using SIM cards. Verizon already has the largest mobile to mobile, the largest coverage area, the largest 3G coverage area, and their prices aren’t any more than AT&T.

AT&T better do something quick or they will be forced to become a low cost bargain carrier (like T-Mobile and Sprint) as soon as next year.

EXisting devices: If your HSPA radio is of he appropriate class (6,7, etc) then you can take advanage of the bandwidth upgrades. Cureently some radios only handle up to 3.6 Mbs, some can do 7.2. But as a practical matter, real world speeds will always be (MUCH) less than the class maximums.