Does not work like most people think it does. People who stopped playing the game to go play other games will not know when an update comes out that they want to play. There will be no update that brings back a surge of players.
Population growth when it occurs will be slow. People who are playing will tell their friends to check out the changes and if that player likes the changes they will do the same. Because when your XBOX starts up you do not see news that says “Hey come check out Halo 4 again” many people will not know of the changes and the effort that 343 is putting in to fixing this game.
“Listen to the competitive community”
This thinking would only hurt 343 more at this point. Most of the competitve players have left and probably do not regularly sign in to Halo 4 to see any changes. The competitive community has always been a minority but a very vocal minority. The best thing 343 can do for Halo 4 right now is appeal to the majority which are players that like having fun and enjoy playing the game as it is now.
The competitive community will most likely never make a full return for Halo 4. In Halo 5 343 will hopefully have them covered right off the bat.
In order to have population growth 343 must focus on the majority and relies on everyone who knows of the updates to bring their friends back in.