Here is a great site for salaries. Where do you think Dez deserves to be on this list?
http://overthecap.com/position/wide-receiver/
I would venture that 5 of the top 6 on that list are contracts full of rue. The Calvin Johnson one is probably rue-neutral (for now).
From an impartial Sabermetrics viewpoint, it likely makes sense to franchise Dez, then take the big money you would owe him on a long term deal at age 27 and invest it in multiple younger players. Let somebody else fork over $100 million and inherit injuries and off the field concerns for 75% of the contract length. It's not a fun concept in the eyes of "Proud To Wear The Star!" fandom, but it may result in more long term victories.
An even better scenario would be the above coupled with a trade for draft picks. But who am I kidding? This is Jerry running the show, not Belichick. The last time I can remember a nice high draft choice trade was Steve Walsh.