It died much faster than that to me. Too laggy and the gameplay itself isn't that good either.
Nontheless it is far from dead. It's the most played game on the wii at all at the moment according to stats. I remember reading that somewhere only about a week back.
Edit: Ok correction. Most played M-rated wii game. Here's the stats (from may 11th)
http://n-club.dk/gfx/news/4436/custom_1242061668326_M-Rated_Wii_Usage.jpgEdit2: Alright it seems to just be overall average time my bad. I still doubt it is anywhere near dead though. Probably still has more active players than MoH ever did.