street fighter is also a game within a, lets be honest here, dead genre. racing games aren't faring much better these days, but i can guarantee GTS's faults will fall by the wayside and it'll still sell really well. 10 -15 million like some of their releases? no. but then i can't imagine sony has that in their expectations either, i think 5 million sales ala GT5 prologue seems reasonable though..that was pretty stripped back in regards to content, way more-so than GTS seems to be.
and you forget the views of forum dwelling gamers don't reflect that of the general population. a ton of people will see a GTS ad and buy it BECAUSE it's GT. will they be disappointed? will they trade it in? who cares, doesn't matter, at that point they're a tally mark on a road to success for the title, and ultimately that's all that matters for polyphony and for sony, and it's reason we will continue to get sequels.