I think they will be quite close by the end of this generation, I mean looking at last gen it was 76:57 in favour of North America... or 80:59 if including the Dreamcast.
previously it was 63:48 (PS1+N64+Saturn) but the American market was growing really fast then, I think American growth will be slowed down this gen purely by population, 76 million out of 350 million is more than 1/5 which is similar to Japan. I think the Wii may be the main reason there will still be growth this generation in America... so perhaps a total of around 90 million.
Europe still has a lot of space for growth, and may end up close to the American total for home consoles (75-85 million)
-----------
On the handheld front I'm not really sure, it seems GB did as well in Europe as in America, yet the GBA did no where near as well, I think that is partly because the DS didn't kill the GBA off so quickly in America, but also because people in Europe were happy with GB or GBC, which may have also been bought more seperately in Europe than elsewhere (eg in Japan most of the people who bought GBC probably had a GB before it, whereas in Europe I think this will be less so)
---------
When gaming becomes commonplace worldwide, which it will eventually (whether the system is similar to now though I don't know) then of course Asian markets outside Japan will become much bigger than anything else, afterall 1 in every 3 people is either Indian or Chinese. (Of course it will take a long time for these markets to grow... probably 3 or 4 generations just to match Japan, although by that time the growth will be incredible so the generation after it might be challenging Europe)