I mentioned the 18+ games part to highlight the hyperbolic nature of the article. It assumed, based on current guidelines , that Skyrim et al. would not be allowed by MS. But that situation is quite absurd because it assumes the guidelines will never change and that MS is willing to lose money on the biggest gaming franchises.
Using extremes like this doesn't support an argument. There is no actual evidence (i.e. non-hypothetical) in the article that MS plans on losing the hardcore gamer demographic on the PC. I don't see any restrictions on developers that haven't existed before. Developers can still program desktop games and avoid the store, just like they've been doing all these years.
I feel there's this illusion where it's either the old, "open", Microsoft business model or the closed down Apple model. There can be a middle area where certain form factors, such as tablets, can benefit profit-wise from a closed down system (iPad, WinRT) and other form factors, like the desktop, can benefit from a dual system (ie consumers can opt for the store, or just download like normal). This notion that MS has and will fully lock down all their platforms seems unlikely to me personally.