There will always be a limit on interested teams in a given year for the reason you mentioned - a lot of teams have their current QB under contract. But there will be interested teams, not just this year, but the next and the next. We have to remember that signing a QB to a long term contract isn't just about keeping him off the free agent market for a single season, it's about holding on to his rights for several years. He can only be franchised twice, and the franchise tag, especially twice, would alienate a QB.
That said, there always has to be a limit to what a team should be willing to pay, but since we really don't know where the two sides stand it's pretty hard to make a judgement.