If there is one thing which really has helped Microsoft get a lot of attention from developers were the - Universal Windows Platform App, but there are a few which might just not want to get into this universe for now.
If reports are to be believed, the owners of WeChat have literally stop further development of their apps on the UWP regine, where as they continue to maintain and develop their apps on the other platforms. While WeChat was amongst the launch partner of Microsoft on the same very platform when Windows10 was announced, neither Viber nor WeChat has really seen any updates or version improvement since then.
WeChat is one of the most popular messaging app in China and if Microsoft loses on this one then they are bound to lose a lot of market share in the country.
We hope not this happens, do let us know your views on the same.