The thing is while a 2 div structure sounds great, I don't think deep down Ireland and Afghanistan can afford to play tests or really care about it too much. So having them stack up a div 2 doesn't really help anyone.
Ideally the initial round would just be Div 1 India, England, Australia and South Africa.
Div 2
Pakistan Sri Lanka, Kiwis, Bangladesh and WIndies.
Now what could make or break this is if big 3 would allow themselves to get relegated. If they don't then the whole thing is pointless...but if they do then test cricket could get exciting again.