Before Sunday’s playoff loss to the Philadelphia Eagles, Tarvaris Jackson was expected to be the Vikings’ top quarterback heading into training camp next season. Now, though, Jackson’s status is unclear. The Vikings might have options to find a starting quarterback, but those, too, are unclear. If team owner Zygi Wilf, who invested $60 million in guaranteed contracts this season, is willing to guarantee an additional $30 million or so, the team might be able to pry Matt Cassel away from the New England Patriots. Besides a new contract for Cassel, 26, the price of a trade would be high — perhaps first-round and second-round draft picks. It’s unclear whether New England would be willing to trade Cassel, an unrestricted free agent who is expected to be designated a franchise player, thus guaranteeing him about $14.5 million for the coming season. Cassel would provide hope for Vikings rooters, retain the team’s visibility and might even enhance Wilf’s effort for a new stadium. A more realistic and practical objective, though, might be to trade with Seattle for Matt Hasselbeck, 33, who probably would be available for a second-round draft pick. The Seahawks, 4-12 this season, need to rebuild.