In today's pipe dream:
Instead of three seats in a row, a bench seat that could be three seats for median adults, two median adult seats and space for two small children in between, or two seats for substantially larger than median adults. Or, you know, people who just hate touching the person next to them, but don't want to pony up for business/first.
Kind of a cool idea. Doubt I'll ever see it in reality, and in any event, my kids are already bigger than the Very Small Child range anyway.