The Vikings lease ends at the conclusion of the 2011 season.Actually, no. You cannot break a lease to move in the NFL. Even the Raiders had to wait until their lease expired, and the Browns/Ravens were able to negotiate a buyout. The Vikings have a while to go on their lease, and Minneapolis doesn't seem interested in a buyout to lose their team. Especially with the NFL leaning away from replacement expansion teams.
The Vikings are in the same boat as the Chargers. They have virtually no leverage.
The Industry stadium proposal would be more appealing to prospective NFL franchises in terms of costs. The stadium uses less steel (it is largely built into a mountainside), is on a wide open piece of land, and doesn't have a roof or need to accommodate basketball/trade conventions. Furthermore, the site appears to be large enough to house team headquarters/training facilities:
The wild card in regards to Industry is Ed Roski and what he will demand from prospective tenants to give up his land for the stadium.
From an owner's point of view, the best site for a new stadium in Southern California may still be Chavez Ravine, all things considered (the McCourt divorce complicates that option).