That number's thrown around a lot, but only TWO QBs (i.e. Brees and Rivers) get it. Spotrac has Matt Ryan at $19½ mil, close enough to call him a third, but even so: $20 million isn't just franchise QB money; it's ELITE QB money. Rodgers is the games best, but "only" making $18¼ mil this year; Mannings pay cut to $17½ mil still leaves him 6th overall. Dalton, Palmer and Wilson are making <$10 mil (even after Wilsons new contract, which some here say overvalues him.) Those guys may not be elite, but few would dispute they're franchise QBs, and ALL THREE COMBINED get $24 million this year.
http://www.spotrac.com/nfl/rankings/quarterback/
If we want another HoFer, yeah, expect to pay Brees $20 mil (and hope NO releases him because he's 1) the highest paid QB, 2) 37 and 3) coming off a bad injury; those aren't great arguments for ANYONE to pay him $20 million/yr.) But it doesn't take a first ballot HoFer to win SBs, especially with a roster like ours; if we re-sign/replace everyone else, pretty much ANY franchise QB could win us a SB or two once Kubiak and Dennison knock the line into shape, because our line was our only real (but critical) weakness.
Now, if we don't think Elway can maintain what he built long enough to develop Oz (or someone) into a franchise QB, finding an adequate placeholder to win a championship while we wait may make sense: That STILL doesn't require a $20 million/yr All Pro; a $10 million game manager can do the job with this team, because he wouldn't have to put it on his back very often, and they could usually carry him. It's not as simple as "HoF QB=SB; no HoF QB=no SB." This isn't Madden nor (other) fantasy football.