Interesting. I would not be surprised if some American Indians came from Jomon. I remember hearing Ainu came from North Asia and now Southeast Asia. I don't think Jomon is from North Asia. I am inclined to say Southeast Asia. Ainus for one have a cult of snake, which would suggest they are from a warmer part of the world. Snakes don't live in that area. Also, many of Ainu housings look similar to Polynesians and Sumerians/Marsh Arabs (M'adans).
Yup. They all radiated out from Sundaland at the end of the last Ice Age, these Jomon 'like' people. Some became isolated during the Last Glacial Maximum(LGM), 18,000-23,000 years ago and evolved the characteristic Asian features and teeth (sinodont). DNA indicates that the Northern Asians are descended from the Southeast Asians.
You need to read Stephen Oppenheimer's book, Eden In The East.