When asked on Tuesday how many quarterbacks he would be comfortable keeping on the roster, Zimmer said, "I don't think we'll be two quarterbacks, if that's the question you're asking."
By saying the Vikings would be unlikely to drop to two QBs, Zimmer effectively confirmed Ponder will be on the team's opening-day roster. Things can always change, of course, but despite how little the Vikings have used Ponder in camp, they still see value in keeping a third quarterback for emergencies. As we discussed earlier, retaining Ponder would give the Vikings a veteran option in case Matt Cassel were injured or ineffective and the team wasn't ready to put Teddy Bridgewater on the field yet. There's a valid line of thinking that such an insurance policy is worth a roster spot, especially when the most important task the Vikings have in the next few years probably is managing Bridgewater's development correctly.
The trick, of course, is valuing that insurance policy in comparison to other roster construction options, and the Vikings apparently put a high enough premium on it to sacrifice some flexibility elsewhere. They've always had three QBs on their opening-day roster with Rick Spielman as the GM, even as some teams changed their philosophy once the league eliminated a rule in 2011 that effectively made a third quarterback a free roster spot on game days.
So there you have it; barring some kind of change, it appears the Vikings will have three QBs on the roster this season. And it's safe to assume, at least at this point, that the third one will be Ponder.