The current Microsoft strategy when it comes to mobile is still one of retrenchment. Microsoft has pulled back development of the Lumia line, including product cancellations, for presumably a few reasons, including:
1.Windows 10 Mobile is still being developed and improved
2.Let OEM partners have some breathing room to create new hardware
3.Give Microsoft time to come back with a strong product and something to disrupt the market
While Windows 10 Mobile has significantly improved with the latest 10586.164 release aka 'production build' the OS still has a way to go before it can be truly competitive in the consumer market. Two major updates – Redstone 1 for summer 2016 (now called the Anniversary Edition) and Redstone 2 for spring 2017 – will bring a lot of polish to the OS as well as new features including deeper integration with Windows 10 for PC.