MvdP is obviously very good but as far as the Tour is concerned I am really not sold on his flat bunch sprint capabilities. I don't doubt he has the speed to be in the mix but I can imagine him not being there consistently enough to win green.
In all the years Sagan won a lot of that was on the basis of simply being there Every Single Sprint.
I would expect Merlier to be their sprinter, possibly with MvdP as leadout.