By 2100 how many nations will there be?

[minionofmidas]

2100 is a bit far away, but the current trend is towards ever more, ever smaller, ever less powerful nations and ever fewer (er...no, probably not that one), ever larger, ever more powerful private corporations, and that'll continue for quite a while.
Increased cooperation between nations, regionally à la EU or worldwide à la UNO, will be the most powerful force against that, but won't mean actual fusing of nations, desirable as that may be.

[minionofmidas]

Continental Europe, minus UK and Switzerland could fuse. Also there is the possibility of a Middle Eastern Empire again.

China will also probably try to conquer some areas. Canada the Caribbean and Mexico will probably go to the US. Russia will stay the same. More than likely an African Empire and a large Latin American state.(unless they become part of the US too which is still possible.)

And either one large Pacific State or the US will probably take them.(we basically control them all anyway(and I mean the SMALL SMALL Island Nations))

Exactly that's the point - you control them anyway, you don't have to officially annex them, you've got nothing to gain from that. In fact, you used to control them directly for 45 years.
No reason to believe this pattern will change anytime soon. It's called "Neocolonialism".

[minionofmidas]

2100 is a bit far away, but the current trend is towards ever more, ever smaller, ever less powerful nations and ever fewer (er...no, probably not that one), ever larger, ever more powerful private corporations, and that'll continue for quite a while.
Increased cooperation between nations, regionally à la EU or worldwide à la UNO, will be the most powerful force against that, but won't mean actual fusing of nations, desirable as that may be.

Nothing much to add.

Oh, yeah, except: Given the massive economic and cultural problems (and political cleavages) created by every country merger these past hundred years or so, I think I'll lay off  the "desirable as that may be" part.