OK, I think it might be interesting to concentrate on that question mark and look for things that are not obsolete now but will be in the remaining part of our lifetime. My nominations include:

iPods - there will be something like them, but I don't just mean style changes. I mean as big a difference as current iPods from cassette-based walkman.

3D films etc. Goes in and out of fashion all the time. I reckon we will have a fallow period soon for another decade or so.

Touch screen phones - the compromise necessary between as small a phone as possible for convenience and the fact peoples fingers are pretty big will lead to a better solution.