About unforseen consequences. I really enjoyed the original movie Bladerunner; watching it recently, it was interesting to see that while there were ubiquitous video phones, there were no cell phones at all in the movie--flying cars yes, cell phones no.
Cell phones and the internet are the two big developments that most early sci-fi missed. They're obvious in retrospect but clearly they were unexpected by futurists in the decades before they became ubiquitous. It makes me very curious what the next unexpected game changer will be!
A glaring example is Neuromancer, where the protagonist is always running around looking for a landline to connect to cyberspace. You would think that by the 80s it would have been easier to imagine wireless communication, but Gibson is famously non-technical, so I guess it's not that surprising.
