OSDev.org

Android applications and services are very popular in today's world. As android is a open-source project, would it be possible for porting the android SDK & its runtime to other operating systems.

I think Microsoft created a project to port applications to Windows RT systems by converting their code. Why can't they just implement a Android subsystem (like Interix, or Subsystem for Linux) to run android apps on the fly.

What would be the possibilities of creating a Android-compatible OS? What problems would be faced by a company in doing so?

I think it's possible, if one needs android. My OS has exactly these ideas of environment subsystems for different user space APIs, inspired by NT's. I am planning/dreaming/working on 2 such:
WinAPI like subsystem, well, a core subset at least, - AvAPI (Avril API, haha yes, I am a fan of Avril Lavigne )
and POSIX kind of compliant subsystem, PussyX, mostly to be able to port existing applications written for this API.

Android is not for me, I just don't like it, honestly, but conceptually it's the same, - you adapt that interface for your OS and vice versa, why not if you want. Of course, it's hard. as always with OS development.