If it was just a Wii with an HDMI port for upscaling, I'm not really sure what the point of that would be.
Either way, 2010 seems a bit too early.
I see Nintendo wisely holding off on releasing an HD console until the cost of components necessary to push HD resolutions is low enough that they can set the retail price at the same price as the original Wii.
Other factors determining a release time frame would be HD set market penetration (no point if most Wii households still haven't made the switch) and any changes in projected sales for the current Wii. This holiday season will undoubtedly play a key part in their future hardware release strategy depending upon how close they are to meeting/exceeding projected sales.
If they decide to go with a two tier product approach (seems likely), I could easily see the Wii SD retailing for $99-149 by then, guaranteeing it sees continued post PS2 slim level sales.
And yes, if having an HD console meant no substandard ports and all the same multi-platform games currently being released on leading edge development platforms, I'd buy one for $250 easily.