I'll echo what several others have already mentioned in that the biggest difference for the most amount of teams is made by available COTS items. The hex shaft system makes a subtle but monumental difference. I don't even want to think about having to use keyways or interference fits or clamping hubs or tapers or set screws every time I want to transfer torque on a robot. I'd love to see hex shafts adopted by real-world industries, but I'm not holding my breath.
As for the next big technological advancement that will impact teams? I'm gonna go out on a limb here and say mid-scale advanced manufacturing services. Already we're seeing things like the Wazer or other small scale CNC machines. While I don't think these are viable for anyone just yet, within 5 to 10 years, affordable CNC manufacturing on an FRC-esque scale could be a thing. Also, mid-scale additive manufacturing is a possibility. A vast amount of teams already have small desktop 3D Printers. There's lots of research and development being done all over the world with large scale additive manufacturing.
*ahem* But to the best of my knowledge, there's barely any work being done to create printers in between the extremes. So I think we'll start seeing additive manufacturing machines much more on the FRC scale start coming from industry R&D, and then we'll swoop in to reap the benefits.