We'll see how the season plays out. My guess is the Vikings will draft a QB they think is the future but might not be ready to start from the get-go. (this article suggests that potentially six QBs could go in the first round). If Cousins would resign on a one year deal so the drafted QB would learn from him, the Vikings would probably do that in a heartbeat. But if Cousins wants multiple years (and he does) and another team would give that to him (I'm sure someone will), it becomes a trickier problem. In that case, I could see them trying to find a bridge QB, whether that's Dobbs or someone else, and then using some of the rest of the savings on other parts of the roster.
But if this team continues to play well, make the playoffs, etc, then Dobbs would be off the table as well because someone is going to give him multiple years. In that case, the bridge QB might be a step down from Dobbs or they just go with the rookie from day one.
On the other hand, if they don't like any QBs in this draft (or they are taken before they can pick one), then multiple years to Kirk or Dobbs because likely.