The end certainly makes it open for sequel. Anyone watch past the endgame credits like i did? Afterwards is a short cinematic which totally leaves the Halo series open for sequal i think. Although i don't think they will ever make a Halo 4.
No way are they going to do that... it already ended for me... i'm happy w/ the conclusion of 3 and i want no more of Master Cheif... never really liked him in the first place...
It's not really halo though...you play as a female soldier and it's just a side story of 3, and halo RTS is coming out soon. I think there will be a four it'l be like metroid differnt chronicles with new plots, but still tied togther.