First, i'd say that it does not have all of the same functionality. Office alone, proves my point. (Yes, there are productivity tools for the iPad, but Office is the gold standard).
Second, no matter how many ipads people have at home (fewer than most people around here would think, even though i can forgive some of you on the basis that you are american, Apples stronghold), owning an ipad wont convince your IT-department not to replace your laptop and desktop with a Windows tablet.
Fourth, im certainly not saying that people will abandon Apple products. There is really no reason to. They are good. It has nothing to do with that.
Last, your point is moot. The argument was that MSFT can leverage their dominance in enterprise to gain a strong hold on the user, the very same user that will later on consume IT in his home, and then quite often so a MSFT product, as it is what he or she has grown accustomed too (it happened with PC:s, so the scenario is hardly implausible). Once more, im not expecting average joe to ditch his iPad the day the Surface is released. Its not about that. There are, however, still hundreds of millions - if not billions - of tablets left to sell in the upcoming years. I think MSFT have a great chance at snagging a substantial share of those sales.