I'll just put it this way. We've got a huge surgical club. Like, well over 20+ members. Last year, we had zero general surgery matches, and four specialty surgery matches total. Most of those people end up going into EM, IM, etc at the end of the day. Same goes for many of the other major interest groups- plenty of people want to do derm, or rads, or whatever, but we get one to two matches in each per year out of well over a dozen people. And the remainder end up largely in primary care. This isn't to say that it's impossible to specialize as a DO, merely that many, many of those that would ideally specialize end up in primary care. Asking around, I'd say that 30% or so of my class would prefer primary care, while over 60% end up there. At an MD school, you need to do everything wrong to end up in primary care if you don't want to be there. At a DO school, you often need to do everything right to avoid ending up in it.
I say all of this as a person who's got a strong interest in primary care, mind you. I just know a lot of my classmates will end up sorely disappointed come match day, unless they have some sort of revelation that they wanted to be PCPs all along come third year.