Going by past updates, iPods are updated once a year, so i would say next September. Only exception would be a big movement on the price of flash memory, in which case we might get a capacity refresh in late Spring.
Yep, jailbreaking breaks the terms and conditions of the warranty. But from what i can ascertain it's easy to refresh and if the touch is dead from a physical impairment, i don't see them not replacing it for you. YMMV