Sales have decreased, but dude people are going to buy Madden no matter what. Its a pop culture thing, every year you hear people say "Gotta get Madden" there are still people out there I know, that play nothing but Madden regardless of the changes to the game. Its always been the game
The only way Madden could stop selling is if EA did something insane like made the Wii version the lead platform and ported that to the PS3/360. Anyway, its still doesn't look good that sales have decreased considering that its the only new option every year. How do you lose customers when you're the only one offering a certain product? Profits should be going up for Madden every year, but the opposite is happening