I'm not quite sure what you're asking. Yeast can only produce alcohol so long as it has materials to do so - specifically, sugar. They will stop producing alcohol when they run out of sugar, or if the alcohol level gets so high it becomes poisonous to them. The alcohol tolerance tells you roughly when that happens.
Unless you make a beer with a pretty high OG, you won't get to 11%. It would take lowering the gravity by about 1.082 to get there. So for beer, if you get great attenuation, you would need a OG of somewhere around 1.090 at least for alcohol tolerance to start coming into play.
Wild beers can attenuate more than monoculture strains - that is, they can reach a lower FG (though it can take quite a while to get all the way down). So I suppose you might get a slightly higher ABV if you use the Roeselare blend than if you use a monoculture.