Points to consider
Cod2/4 players that this game was designed for are all 25+ approx. This means that probably half of them may of gone onto other games, 'hung up their mice', or not want/able to commit the time required (family/work etc)
The new fresh blood that really kickstarted cod4 was on the back of cod2. The game was current and established and community clans were thriving with 20+ servers and their own websites. Not to mention the 'apply to join Osiris' link (little name drop there to a community team)
There is a huuuge skill gap with new players joining and although all of us accept jumping around corners, if you are new its a hard game to master and there is little in the way of casual enjoyment.
I think you need to accept that unless this game is picked up by the 'fresh-blood' then you will only get 3k max players (with a decent wind in your back). I personally think that the tournaments are not going to kickstart as predicted as there is no playground for the new guys. Play ranked, come up against a fucking beast called Gunjax, lose and then say game is shit. (there is some humor in there before you keyboard warriors jump in)
Just remember all this, if you enjoy it, play it. COD4 is gone, the reason its gone is because we all left it.