American Football?!?! It’s Six Nations logic, ya flamin gallah! Although I think you play the final at whichever country finished top of the league, which is a bit NFL.
Regardless, I think the ICC needs to independently (and I’ve got vague hopes for this, certainly more so than 2 years ago) take control of international fixtures. Leaving it up to each country has resulted in far too much cricket, and a money now mentality rather than ensuring the best future for the game. Personally, I think all series should be 3 or 4 test matches. I find it ridiculous that the second tier test nations are expected to be able to improve playing 2 match series.
Not sure about ODIs and 20/20s - could either go for equivalent number of test matches OR do a tri-series in between the two test series (when possible), featuring the 3 nations involved in the two test series.