I would argue that's even harder for them than FirefoxOS because at least with FirefoxOS, it's powered by web technologies and you can have most basic apps without much work. Whereas with Windows Phone, you need actual developer time to create an application in the new ecosystem. It's already hard to convince people to port applications but it's even harder to convince them to redevelop something new entirely.
Not exactly true. You can build Web Apps for existing Windows Phone devices and Windows 10 mobile, you can import your iOS or Android apps directly to Windows app store.
What you are talking about? Importing iOS and Android apps into the Windows app store? There are some announcements, that this might be possible at some point in the future. But at the moment nobody knows how much modifications will be necessary for the apps to run on a windows phone.
