>>1Rootless presentation of applications can be done already. There just aren't reliable, well known free tools that support doing it. Microsoft markets the technology primarily to big corporate customers who demand good VDI for Windows, not for individual use. The situation on the host side of things is slowly improving (FreeRDP finally has near feature parity with old rdesktop, for example) but the guest support is still spotty.
Frankly I'm not sure it's realistic to expect free software to provide this either. Microsoft just doesn't want end users to virtualize Windows. Overcoming that means dealing with lots of headaches of the kind that drive away volunteer developers.