The roster is never done changing. The Vikings have a 53-man roster set, but there's a good chance that because they changed their mind on Michael Mauti and their expressed interest in offensive line depth, they could very well go after players that weren't around for Vikings training camp.
Naturally, the trade for Jeremiah Sirles alters things (and the Vikings changing their mind on Mauti could have been related to Sirles), but it's worth taking a look at some players that are at the very least intriguing.
Last year, the Vikings added two players to their roster that weren't in training camp and one of them is now the starting right guard for Minnesota.