I'd agree that caching is important, but when, realistically, would you not have any sort of wireless access in 20 years? Driving? Many cars these days have hard drives; it's easy to see that becoming more prevalent as storage gets even cheaper. The people designing mobile devices aren't worried about a single farmer in the middle of Saskatchewan. Cell phone providers didn't even bother with the
whole of Saskatchewan for a number of years.
If you can get a cell signal, you can get streaming media, or at least you will be able to. I don't see that being much of a problem.