Re: Developer support depends on Microsoft delivering the right eco-system
As far as I understood, the platform API changes from 8.x to 10 are nil: you get to use the same Modern UI and the same platform interfaces. This week I changed my phone from one running Windows 8.1 to Windows 10, and all 40-something apps I had on the old phone were re-installed from backup without a hitch (some actually started to work better, go figure). I don't think all the app vendors had to change anything in their apps in order to make that happen.
Biting the hand that feeds IT
