Basically, Microsoft just wants one OS they can use across all devices, it makes things easier on their end, and they had the hope it would help increase adoption of windows mobile devices if people were more familiar with the OS from using it at home. It didn't turn out very well for them with Windows 8, but 10 is meant to be the best of both worlds, so we'll see how that goes.
Compatibility is going to be an issue, though. If Windows 10 adoption is widespread (it should be, it's free for 7 and 8 users), maybe companies will be more proactive in releasing compatibility patches/updated versions. But aside from that, you'll have to use virtual machines, which actually work fairly well with VNs.