It's important to note that not all the comparable contracts below worked out well. He's not quite as good as 2010/11 Paul Martin, and lacks the offensive upside of Sekera. 4 years is the absolute maximum term he should get, and even that might be too much. He blocks more shots than anyone in the league. I'm sure his body is dented in several places. It will be difficult to sustain that punishment into his 30s. The 4 year $16M deal seems like the most palatable overpayment, but I think if he were willing to accept that, he'd have a contract by now.
There is significant demand for Russell at the right price, but not at the wrong price. Cody Franson went through this last year and he's a better player. Buyer beware of the long term sustainability of this asset. If he can squeeze up into 5 years $20M we're probably looking at a future candidate for one of my worst contracts lists.
*Note in 2007 and 2008 the salary cap was down at $44M - $50M, and it's over $70M now. There has been cap inflation, but that doesn't change my valuation of Russell. I don't think he's in the class of player who has benefitted from cap inflation. I don't think Jay McKee's contract from 2007 is $6M AAV in today's money. Some things change, some things stay the same.