i think its a fantastic idea. would certainly increase the competitiveness in both federations and could reduce the gap to Europe if USA takes this seriously and starts investing more into football. if it would inspire the US to invest more into football, have better broadcasting, make better sponsorship deals etc., this could become one amazing project.
there are some problems though, like huge distances between some cities, which could be solved by making each group (im assuming it would have the same format as the European CL) play in a host city. but if it is played in host cities, when is it gonna be played, because the season is ongoing and it would be hard to fit in 6 games in the middle of the season with the national leagues etc. it could also be solved by grouping teams on regional basis, which would make teams closer to each other playing in same groups, but that would go against the main idea behind this, which is making teams from USA compete against South American teams. another thing is the financial gap between USA and the rest. in the beginning it should be no problem since the SA teams have more quality, but in the future it might present a problem (IF the US take this seriously like i said above). imagine the most talented young SA players going to USA instead of Europe...
as i said, the idea is fantastic, id love to see such a league, but im still not convinced it would work so well. looking forward to see how these issues are gonna get solved, if this league ever lives.