> Granted didnt Phobos slam into Mars too? I don't really know when that was supposed to have happened.

50 million years from now, if we don't mess with it. By then we could have mined it for raw materials, or turned it into an anchor for a space elevator.

We don't know how Phobos and Deimos came to be, but one idea is debris kicked up by an asteroid collision, that then came together by gravity. There are plenty of big craters on Mars that could have been a source.