I am not sure if I agree with that - I think absolute numbers are also going down, but the "hunter intensity" is going up. By that I mean hunters seeking 4, 5, 6 tags; hunters going to 2, 3, 4 non-res states in a season; going hunting out west hunting every year instead of a once or twice in a lifetime experience.
I don't think the number of hunters is the big pressure point - it is the more committed hunter's expectations that are the biggest pressure on game. If everyone was limited to 2 big game in-state tags and 1 out of state big game tag then I would guess a lot of tags would open up even with current animal numbers.