> Is anyone else skeptical that they can motivate publishers to spend time/money porting their games to the Linux platform?

no.

porting and refactoring tools are so good now you can even port a direct3d app to opengl in 2 days or less, you could use a d3d>opengl wrapper in a day of work.

libraries are also so good at dual platform it requires minimal changes (usually just a new build system).. afaik the biggest change is handling input (theres no directInput on linux - most games use directInput for mouse/kb).

theres also numerous benefits to a closed system economy like an app store - for example even if nobody uses it you are practically exclusive and will get more buys than other places you can sell your app.