I've always had a fondness for alternate histories and that was one of the
enjoyable elements of this story and I would like to see more of this
alternate Japan.  However, I think you should give a little more
explanation for your alternate Japan's development.  In particular, the
position of women.  In the real Japan, women's professional opportunities
are still rather limited.  In the  alternate Japan, it seems as though they
have as more opportunity (based on the description of Nabiki), yet a Japan
in a world where the US never developed and didn't defeat Japan would
likely be more traditional in its social institutions.  (The Kuno's lineage
will actually matter.)

Are both Ranma's fundamentally identical as far as mental and physical
potential?  Will alt-Ranma be able to reach Ranma's speed and strength?
(Ranma is weaker than Ryouga, but is still quite strong.)  Does Ranma now
understand quantum field theory?  Is Ranma a budding Nobel physicist? Even
given the knowledge (and personality) transfer, I don't see alt-Ranma
having such an increase in fighting ability as shown.  The speed and power
come from years of physical training.  

Will the curse also transfer?  I'd argue against that.  In the alt-Japan
you've shown, his curse would not simply be treated as a curiousity.  Were
the government to become aware (and with Nabiki on campus, they would be),
he would be bundled off to a research lab for study.  

                                               dml