This is their play to get their own app store. If they can get a 30% cut on all games involving DX14 for example (by obliging DX14 games to use their app store), then they will be raking it in. There is no way they will give up on this strategy, as the benefits are too high.
Personally I say fuck them, they shit on PC gaming with GfWL because they were focusing on xbox, so I'm glad that Steam ate their lunch while they weren't looking. To add insult to injury, there are games now that are defunct because they relied on GfWL which was then abandoned by MS.
It turns out that Gaben was right all along about the need for SteamOS.