Well, I wouldn't go so far as to say it is not possible. Not feasible, perhaps...given the HUGE amount of work that would need to into porting it (as others have noted).

Now, it is not "possible" for *me* to do it (It would take a lifetime for me, personally, to do it) but a determined group of smart people could do it if they wanted (a "Mer" like project) though the hardware limitations might put a hard cap on what was ultimately able to be accomplished. Just my 2cp.