What if Sweden, Turkey, Venezuela, Argentina, and Iran joins the Axis and Switzerland and Portugal joins the Allies? Will the war last longer? Will the Axis have a better chance in winning? Please give me your thoughts/answers.
Oh, cool scenario.
Ok then, first off, you could see Brazil and Mexico joining the war on the side of the Allies. Chile might get involved too. This could turn the South American theater into a real part of the war. Turkey and Iran being in the Axis poses a major threat to the USSR and to British oil supplies in the Middle East. Expect that to be a much bigger theater than OTL. Switzerland joining the war in unlikely, due to its neutrality clause. Portugal joining would have a negligible effect, but may have the horrifying side effect of pushing Spain to join the Axis.
Ultimately, though, I'm not sure how much it changes in Europe. The Allies still have a ridiculous advantage when it comes to manpower and industry, and the factories of America and Canada are still untouchable. Best case for the Axis, they cripple the USSR, only to be defeated by the Western Allies sometime around 1946-1948. Worst case for the Axis, Soviet tanks roll into Istanbul and Tehran in about the same timeframe.
In the postwar era, you would probably see much closer relations between the US and South America. Brazil would become a major US ally too. Instead of NATO, you might end up seeing ATO (Atlantic Treaty Organization). Long-term, it's possible that American aid could help kickstart industrialization in South America, which will make the continent much more developed in the long run.
Edit: On second thought, there is one way to get Switzerland into the war. Just have Germany invade. I wouldn't mind reading a TL where Fortress Switzerland become's Hitler's version of the Peninsular War.