I cannot see how One league would work with the current talent pool of riders available. Riders riding for 2 teams in one league is simply not an option even if there was some North/South split for the regular league season ahead of a champions of champions play off. The only way I see one league working is working on some kind of arrangement(if it’s even possible) to allow some of the young unattached riders from the USA, Aus, South America and some of the less common European nations.
However, that then leaves the problem of costs of these riders coming over for machinery, travel, accommodation, working visa’s and whether they’d even meet the criteria to be able to come over here and race under current laws (something I’m not too read up on). Then the question of whether they’d even want to.