They are definitely losing sales from me. There are lots of games on 3DS that I would love to play, but I do not want to purchase the handheld as I cannot stand playing on a small screen looking down at my hands all day. They can easily resolve this by doing one of the following:
1) Make 3DS games available for purchase on the Virtual Console (and make them available to play on 3DS as well)
2) Create a device similar to the Super Game Boy and let us play 3DS carts on the Wii U.
3) Allow the Wii U tablet to be replaced by the 3DS and let the 3DS play full-screen. (For the next revisions I guess)
Seriously, make it happen! Man I want to play some of those great games. They just need to unify the library and allow cross-buy/play and all that goodness.