Seeing as I hadn't seen this forum before I posted in it the other day, I will give my view on it:
I am very much for the six nations being expanded and I've been saying for quite some time that Georgia deserve their chance.
I am a fan of the USA national side and I feel like the country might finally be realising their potential. With regards to whether they should be in the six nations? For me it's a no due to the distance and travelling involved for all sides involved. IF the USA was in Europe then I'd say 'heck yeah get them in' as rugby is apparently the fastest growing sport in America. However, this tournament isn't the one for them and besides they already have their own tournament in the ARC which they have developed very nicely in. They have won the previous two tournaments and have won their last 9 out of 10 games in it. I would argue that they have outgrown that tournament now and unless Argentina decide to put out a stronger team (not gonna happen) then they're going to win it consistently from now on. The side level with them in the rankings, Uruguay, they beat by 50 points which is an excellent show and it shows, to me at least, that they are far too good for this tournament. But the six nations isn't the right tournament for them because:
A: they're not yet good enough, maybe in a few years they will be.
B: it's a European tournament
C: there's way too much travelling involved.
My opinion is that they should breakaway with Japan and a few other countries to down their own tournament. At least then the USA won't be playing teams like Chile which is of no benefit to them whatsoever - beating a side by 50 points every game is not helping anyone out. The ARC would be competitive enough without the USA who, this year at least, were a class apart. The potential market in the USA cannot be ignored and must be nurtured and carefully planned out.
The six nations cannot be a closed shop and it must not continue this way for the sake of developing countries such as Georgia, Romania and Spain. Spain's rise is a good thing as they have money, a large rich population (in comparison to Eastern Europeans), and they have a large potential market there. Hopefully, should they keep developing, this will prompt the organisers to look to include other teams in the six nations. Just not the USA, this is the wrong tournament and the wrong time for them.