You would most likely have ended up with a bleeding edge open source version and several more conservative closed ports.
Bear in mind that a lot of the reason Linux development is strong is because many of it's developers are paid to work on it and then contribute back (again because of GPL). If a company could gain a competitive advantage by paying the same people to work on a closed fork..
I agree though, someone would try. I just think Linux would have done just as well with a BSD license being released at the time it was. The people and the timing deserve more credit than the license.
I strongly disagree with this phrase. I'm not saying making Linux usable is 90% of the work; it isn't, but it isn't "the last mile" either (maybe that + customer support + developer relations and evangelism equals to 15-20%).