I don't see having two tiers helping improve the standard of Test cricket.
Whatever changes are made should be done with the aim of improving Test cricket, both it's overall standard and to keep it as the ultimate form of the game.
I think tiers are the only way forward, until such a time Test cricket will remain stagnant and some series uncompetitive like this. The pros are :
- less teams to play in a rotation = less fixture congestion
- sides play other sides at the same level
- the format becomes workable with a proper table and championship
- series lengths become standard rather than agreed by the two sides
- the game becomes more international with more than 10 elite teams in it
- weaker sides can improve and get promotion to aim at, it isn't just playing cricket and a string of meaningless results
- you could impliment a "deciding factor" of say wickets* to make sure there are no dead rubbers and sides have something to play for even when up against it. This could decide league positions like GD in football
- DRS would be mandatory as part of the competition, maybe just in the top league unless someone funded it in other leagues (or s*y cough up)
*I've long thought margins should be standardised to runs or wickets. Runs as a margin could be say in ODIs the second side bats to the end of their overs so the winning margin is runs. As pitches vary you could do it as wickets, so if the side is batting last and loses by 72 runs say, the margin is how many wickets the other side had 72 runs from the end of their innings (if you subtract 72 from their 2nd innings).
If a side wins by X wickets then all well and good, if by an innings you add 10 wickets to the 72 runs example. As the wicket margin would factor in the pitch, same for both sides, it would be less influential. And of course it means you could only have a "deciding factor" of 20 max, more likely to be between 3 and 10, so it doesn't gain too big an advantage if you win by a lot of runs - and it takes out the complexity of the innings margin for which there is no runs value possible.
I'm sure there are more pros to the tiers proposal, it will meet resistance because people like things the way they are even though cricket itself wouldn't change and the only possible loss is the aussies not getting to stuff the kiwis all the time. When the kiwis are good enough they'll go up and get a chance to prove it, or go back down. If sides are worried about bilateral series they really want in the calendar, with reduced fixtures they could always play each other with the result not counting towards the championship.............................