I think that it is best left the way it is. If you do change it make sure that you test it playing as each country as to not give a biased advantage to your fav country.

K rizma, as for your idea it could work, but if it is used be carefull with it or you will eventually turn your game into an oversized game of RISK.

Of course that is just what I think and hopefully you can come up with a way for it to work better than the way it is already.
Good luck.