The game is not declining at all. If you saw less people in the wsop this year I can tell you its because online poker rooms weren't allowed to buy people into the tournament when they ran their qualifiers. The only thing they could do was put the money into their online account, and then hope they showed up to play in the tournament, of which many kept the money and din't play the tournament.
People are finding new ways to deposit and it is starting to get to be just as easy as it was before. Look at the numbers of people online everynight between pokerstars, UB, fultilt (huge increase this year), and bodog, not to mention party still gets several thousand a night.
The game is not declining one bit.