I think the salient data point here is that Microsoft has just done a total reset on Windows Mobile.
From an app perspective, it means that, as a poster above stated, apps are being developed almost from scratch for the WinMo platform, which means that there will be both a lag in new apps coming out and some feature-disparity compared to apps on more mature platforms. It's also important to keep in mind that Microsoft's mobile platform market share is right now microscopic compared to the big two. So, right now, if you're in a software product group, inside of Microsoft or not, you're going to want your application(s) to be best-in-class on the leading platforms. It would be foolish not to.
From a "commitment" to the WinMo platform, it means that Microsoft is investing a massive amount of (limited, even for Microsoft) resources in that platform. If Microsoft were not committed to WinMo, it could have saved a whole lot of money (and headache) by just letting 8.1 die on the vine. They haven't.
In the short term, this means that the app gap, both in terms of quality and quantity, is and will remain very real. It means that the WinMo platform and app ecosystem will be developing very quickly (as we see with the OS and app updates and releases). In the longer term -- one-year plus? -- if Microsoft is successful, we'll see a vastly improved mobile OS with a few important differentiators, and a significant closing in the app gap.
For now, fasten your seat belts. It's going to be an exhilarating, and bumpy, ride. Buckle up and enjoy!