I really did not want to see this fight. Both of these guys are in my top 5 favorite fighters and now one of them has to lose. Assuming Henderson is under contract by then and agrees to the fight. My guess is they throw a bunch of $ at him to take this fight, instead of the promised bought with Silva.
Henderson is favorite fighter of all time. I have been following him since his first fight in the UFC. That being said, I think this is a bad match-up for him.
Striking - Marquardt - Dan has a dangerous right hand and a chin of granite but Nate just seems more well rounded and technical in the striking. A Henderson KO is certianly possible but I think we are more likely to see Marquardt out point Henderson in the striking.
Ground - Even
Henderson on top - Marquardt is probably good enough on the ground to aviod damage but probably not good enough to submit Henderson. Dan will definately have to avoid submissions and this will probably stall any meaningfull GNP. Again, a TKO from this position is possible but Henderson contolling position and scoring some points is probably more likely.
Marquardt on top - This would be bad for Henderson. Marquardt is good enough to work into a dominant position and probably doesn't have to worry about being submited by Dan. I would honestly have to go back and watch some fights to see how Henderson is off his back. I seem to remember him not being that active.
Conditioning - Even
Both these guys can go three rounds full steam.
I am thinking it's either Marquardt by decision or Henderson by KO/TKO.