Just for fun:

Of US N8x0 users, maybe 1/3 (figuring equally for AT&T, Verizon, TMobile) are currently on TMobile, of that maybe 1/4 are near a point where they can get out of there contracts (+-3 months is 1/4 of 2yr) so roughly 8-9% could get a subsidized phone w/o substantial cost to get out of current contract. Double that for the folks that don't care. 16-20% of current tablet US tablet users could get a cheap / don't care about cost N900.

I'd guess that due to lock-in and contracts, adoption will be slow here in the US. Many of us are in the same boat as GA, too expensive to switch (in terms of money and coverage).