When I was in Bali there were several varieties. They were smaller than Cavendish, but all were perfectly pleasant to eat so I wonder why we can't have those in the US and Europe.
Can't this be solved by improving the transportation of the less durable varieties?
The question is whether there is anything that can be readily made commercially viable and used for the role that we use the Cavendish now.
Most of the rest of bananas out there are not very much like the Cavendish we're used to (though some of the small ones are yummier-- if they could be made more hardy it would be worth getting used to eating tiny bananas ;).