If Halo 5 was anything to run by, then yes, given how everyone was screaming "HALO'S DEAD! DAMN 343!" and then a few months later the guy who works at the bloody company said it was around 5 million... Then everyone downplayed it because reasons...
Well, if we're gonna be honest, 5 million for a main sequence Halo game just about is dead for the franchise. I have no idea where Halo 5 landed, but it is certainly well off from Halo 3's peak. OTOH, if main sequence Halo games can consistently sell 5-6 million every release, then there's no reason it should be discontinued.
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
"When the power of love overcomes the love of power, the world will know peace."