As a policy the soviet warplans mean they would have nuked France regardless .... too risky to have france as a undamaged base.
I've always felt that France escaping WW3 relatively intact was more than a little odd myself. In fact, the plot of France escaping WW3 worked better in 2300 than it did in T:2000 - the world was different with France in charge, but not so different as to turn off the majority of RPG players (US and Western Europeans) who expect a world essentially like ours today.
Unfortunately there's not much hope the rest of the world could maintain even 1950's technology with that part gone.
True, I think a lot of the of the other potential power players could be essentially ruled out, I think: South Africa would probably be struck by the Soviets as SA would likely support the NATO nations with strategic materials. India and Pakistan fight their own nuclear war. Japan's US bases would get hit, as well as other places because you can't really be neutral in a fight in the Far East between the USSR and China and if that didn't work, Japan would crumble due to the nation's reliance upon imports. New Zealand and Australia would suffer a similar fate to Japan, I think, for similar reasons: Both identify very strongly (over strongly, I think) with their Anglophone character and would probably be involved in supporting China at the behest of NATO and US and would become appropriate targets.
There is an area I think might come out reasonably unscathed: South America. While places like Peru or Chile are probably too minor to matter, Brazil (Brasil) or Argentina I think would have had a pretty good chance to come out in good shape. While those two nations had more than their share of problems like corruption and economic malaise, suddenly being the biggest fish in the pond means quite a bit - both nations have resources, plenty of farmland, and a decent (if not spectacular) industrial base. Most importantly, they'd be likely to sit out a NATO-China-WP war and being in the Southern hemisphere, the weather changes from the nuke exchanges could be milder or the onset delayed, giving them time to prepare. In addition, I think Venezuela's oilfields get hit (I don't remember) but for countries relatively untouched, I don't think it'd be that hard for them to get oil production working in Venezuela (this is assuming they don't know about the offshore finds near the Falklands or off the coast of Brazil).
An alternate 2300 with the ANZAC nations, Brazil, and Argentina as world powers could potentially be quite interesting (or at least on par Europe and North America), though I think it'd be too weird for the sensibilities of Ameri- and Eurocentric gamers that make up the majority of RPGers, though.