It would seem to me these could be classes. Some baseline standard with the option to extend(s) as each dev see fit.

That said (and thinking out loud), I'm not so sure this is really data portability per se. This is closer to data standardization - which given WordPress' Wild West approach to growth / market share is a 180.

Perhaps instead it would make sense to have some sort of XML (?) defined mapper between one plugin and the next? That would still give each dev the liberty to move ahead and the users a backdoor to switch horse if they want to.

Heck, a great start to that would be an XML export / import standard for plugins setting. Wouldn't it be nice to config a plugin in dev and just export / import the setting over to production?