Since this is a wishlist - built in battery grip would be great!
Built in? you mean a 1D form factor? What about the people who want a lighter body?
make it in two bodies type, one with integrated grip and one without. that feature will be a premier in DSLR market.
....and the price can be under $2400 ( say $2399 for the gripped one and $ 1799-1899 for the normal body). i personally believe that the gripped one will have more success.