Are you forgetting the last generation?
Sony was able to pull back their catastrophe of a launch and after a very long time even overtook 360 sales, and that was with a large disadvantage in release times.
Microsoft could easily do the same thing this generation. Its far too early for anything to be decided or requiring "miracles". Even more interesting are the other platforms available today and coming soon that may alter the typical sales of consoles in the long term. Again everything is very uncertain, this gen more than any
PS3 launched way, way after and pretty much closed the gap with the 360 continuously from the get-go. There was no turnaround at any point, really.