To come back to human-machine interaction, we think that the successor of the mouse (also for mixed reality for office) sees a much faster adoption rate than the mouse in the last 50 years. At least, we have bet a few years of our life on it with https://www.indiegogo.com/projects/coolest-mouse-ever We can tell you in a few years, whether our assumption was correct :-)
Quantum computing, cryptocurrency (Bitcoin with its 10tps vs Visa is analogous to Engelbart's GUI vs MacOS), lots of AI stuff that can kind of just barely be intelligent today, the Boston Dynamics robots, self driving cars, and last but definitely not least early DIY bio hacking / anarcho-transhumanist stuff and DIY medicine (search for Four Thieves Vinegar).
The things I listed are at varying levels of maturity and gravity but they are all things I expect to look back upon as "wow" moments that revealed new things that will be big in the future.
I'm sure others can think of more.
Can we get to a point where battery tech gets cheap enough that electric personal transport gets even cheaper than ICE cars? Does that bypass mass transit? We've seen futuristic visions of how that plays out, so not quite the reality yet.
At some point, nations at risk will start seriously exploring geo/climate engineering solutions. If adopted, what are the potential side effects and side products?
Innovation is typically more lucrative than invention. Creating whole new ideas and experiences drives the our body of knowledge further, but the rewards only start to accrue to society when those ideas are combined together with an advanced ecosystem that allows mass adoption.
I remember watching Russian TV from the US broadcast over the dial up in 1998, probably on realplayer. This was an amazing experience, magical even. I then and went back to my (CRT) TV because, well, an audio and video stream transmitted over 56k sucked.
It took another 8 years and billions of broadband infrastructure investment before YouTube launched.
I actually wonder more where are the amazing demos of today that aren’t yet economically feasible, but might get mass adoption in 40 years of infrastructure build out.