I don't see why the real core gamers would've left in the first place. As my sig shows there are plenty of core games on Wii already and with Punch Out arriving next year (and rumors of Pikmin 3 & Kirby Wii) along with 3rd party titles such as Sin & Punishment 2, MadWorld & The Conduit the Wii is a solid choice for the core gamer.
Manchester United 2008-09 Season - Trophies & Records