The recent ashes series has opened our eyes to how great test cricket is and this has been the trend when big teams face off against each other especially if they have a rich history in matches between each other. It's not just been the ashes. The battle between india and pakistan and before that the rivalry between australia and india. But then we see pointless tests such as india versus zimbabwe. I remember reading somewhere that the ICC is considering introducing a two tier system where there are top teams that play each other and the second half play each other. After two or so years one side is promoted from the second half of teams and one side is relagated from the top tier. IMO this would create closer competitions and would revolutionise test cricket for the better.
My top tier
and the second tier
another option could be to cut zimbabwe and bangladesh or give them an ultimation to win atleast 2 tests (not including games against each other) in around 5 years.
Atleast after these steps taking place there will be constant great test matches