There will most definitely be more support for the GSM version, as it will be sold in the USA and the rest of the world. The LTE version will only be sold on Verizon in the USA.
If the G2/Desire Z combination is any indication, having thousands more people outside the US with almost the same phone as the T-mobile G2 has brought huge amounts of development to the platform.
But overall, FWIW the phones will be pretty darn similar, and the only difference should be the network stack required for Verizon's LTE network to be added into custom ROMs. There will be plenty of people on VZW with the GN to develop ROMs. It might just take a little extra time because VZW's official updates will no doubt be slower coming out.
Sprint HTC Evo 4G
Motorola Xoom WiFi
T-Mobile HTC G2
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