Do you think gta4 will be the top seller game? overcoming mario, halo???

well with all the hype and the fact that this gta4 will be on both console the 360 and the ps3 that the gta4 game will sell more games than any other game out there ever!? just curious on what everyone think i already pre-order mine and already set up a countdown on my myspace to let everyone know what i'm looking forward to...give me your opinion let me know if your going to buy the best game ever