You can't solve a problem you don't understand. Before you can address the issue of sustainability, we need to figure out (in more certain terms than just a logical debate) why teams are folding.
I know IndianaFIRST surveyed teams that have folded over the past few years. The results were presented at a statewide mentor meeting, and can be found below. I hope that other regions within FRC can implement a similar survey.
Now two of the top three reasons have been discussed here. The one that hasn't, which seems to be the most prevalent among teams in Indiana, is lack of school support.
What can we do to make FRC more appealing for schools to integrate into their programs? There has been talk recently of forming an FRC curriculum; based on this data that would go a long way in improving sustainability.