No, I don't think that Bioware would be done if Inquisition is bad. Yes, it would be one mistake of many and these mistakes are not inexpensive. However Bioware, in my opinion, has a lot of credit already and it would take a lot to dissuade me, and probably some of you, that Bioware is no longer a good company for producing quality games.
First of all, let's not forget that they have a fairly good track record. They created the Mass Effect series, which has had a deep impact on games at multiple levels. So much so that the ending infuriated us because it was a terrible ending to a great story. One does not get angry over a bad ending if the story and gameplay are bad too, correct?
They also created the Dragon Age mythos and while many claim it to be another version of a D&D world (elves, dwarves, wizards, knights, etc.), there is a fair amount of originality to the world and the stories that are shaped in this world. From raging caste-like ogre-ox-men to the eternal struggle between guys with swords and guys with magic being played out in an actual political struggle, Bioware created a fusion between traditional and contemporary fantasy elements to give life to their stories. This originality mixed with things that we find comfortable makes a series fun to watch.
Then, there's the gameplay. Not many people accuse Mass Effect or Dragon Age of being clunky or difficult to maneuver. The combat in these games is usually solid and the other mechanics of these games make these games interesting as well. Sure, a lot of us got tired of the repetitive fights in DA2 as well as the same areas explored over and over again. However many game companies do this much more blatantly, we just expect more from Bioware.
Which is why we're having this discussion. We expect so much from Bioware because they produce good games that keep us hooked for hours with replays and retries. Even Dragon Age 2, with it's missteps, it's still not a horrible game and many of us have played it through once or even two or three times. When a Bioware game comes out, we have very high expectations, ever since Knights of the Old Republic, because Bioware is not a typical game company. It sucks that they're owned by EA but this doesn't stop them from putting forward good products. I think that their record speaks for itself. It'll take a lot more missteps for me to stop giving my money to Bioware.