Adding bodies (help)
Buy a D700 just after the new cameras come out to make the most of the full frame glass you have, when ebay will be littered with them (abeit neither of mine) then get a D8000 in a years time when the D7000 is updated.
Buy a D800 or whatever (only) that will do FF and decent video (probably) but spend alot more.
lugging 3 cameras is not much fun I reckon.
my 2p worth.