I don't think Smash will outsell MK8. If Smash releases as a Wii U H/W bundle (including Gamecube controller) those who've been waiting for Smash to get their Wii U will pick that up, and are more likely to pick up MK8 as a second game.
Those who've been waiting until the holidays to pick up their Wii U for MK8 will pick up the MK8 bundle for their kids but may or may not pick up Smash as a second game.
If there's no Wii U Smash bundle, it will be a missed opportunity for Nintendo.
If there's a deal in the holidays involving both games, sales will soar.







