Turnip type. It's bound to happen.
Nah, anyway, I'm not sure about new types. It'd be cool, yes, but there'd be all of the complications with balancing and re-typing issues, probably adding quite a few attacks, too (they can hardly have an entire new type and only have it having one attack).
If they were to do it, it'd all depend on whether they did it well or not. I don't think many people would complain if they added in a few new types and balanced them really well.