Tyre widths have increased as the population is getting fatter. I know I am. I don't see this reversing anytime soon so am looking forward to my gp6000s in 42C.
The current fat frame tubes are like that simply to make the overweight rider look less ridiculous. They will therefore increase more. Probably the limiting factor will be "can we still get a water bottle in there?". Swat boxes will be so big you'll be able to fit a whole bike in them.
Gearing will go to 1x because the front derailleur confuses the general population.