The (road) bike I bought 25 years ago is very similar to my current bike. (The derailleur on my new bike adjusts exactly the same way). The materials of my current bike are vastly different than the old one. Other than that it's all the same.
What are upcoming bicycle innovations, and if so what?
Considering the comments
I dunno about upcoming innovations, but I reject the idea that nothing much has changed in the last 25 years.
Bike lights have improved enormously. I started cycling with the big EverReady-style lights that took two enormous D cells and gave only a few hours of rather weak light (that is, if the bulb didn't fail). If you wanted to ride for moderate distances in the dark then you had to use a dynamo that dragged like a 30kph headwind while you were moving and went out as soon as you stopped.
Now my rear LED light lasts all winter on two AAAs, and my high-power front LED is good enough to ride all night on dark country lanes on four AAs. Dynamos have improved too, with hub dynamos and standlights the norm.
GPS has made a big difference to navigation. No more staring at maps in the dark to figure out where on earth you are and why that junction that you should have reached 5km ago has stubbornly failed to show up yet.
Online mapping makes planning bike rides much easier: a route-planning task that used to involve covering your floor with maps and marker pens can be done in a few minutes on your computer. And you can check out the awkward junctions in Google StreetView so you won't get lost.
Mechanically, the advantage of the upright bike is its simplicity, ease of repair, and standard parts. There can be tinkering around the edges: better materials, cheaper parts, slight improvements to ergonomics (like brake-mounted gear levers). There's nothing much that needs doing to improve the machine. What we can improve is the way we ride.
Folding bikes are getting better and there is still a long way to go in finding the best folding system.
Low maintenance is important for a lot of people, so better fully enclosed gears, chains and brakes are important to get normal people cycling, likewise with puncture-resistant tires.
It must be possible to come up with better locking/tracking systems. There have been lots of advances in practical light systems over the last few years, this will continue.
However all the above must be cheap enough that they come as standard on a “cheap” bike brought from the local supermarket; otherwise they don’t have any effect in the “real world”.
I see the biggest need for innovations being aimed at people who see a bike as a transport solution, rather then an object to worship. However most innovations are created by and for people that love bikes.
(My wife can own and drive a car, while knowing nothing about how a car works; she just has to book it into the garage once a year when they send her a reminder [or a "error" light comes on]. How can bike be made as easy to use and own?)
Electric gadgets on bikes (while available now) will become mainstream.
Electrical bikes, not the ones your grandmother uses to go shopping, but electrical race- and mountainbikes. Implemented using invisible and low weight devices like the Gruber Assist.
You could also think about electronic shifters like the Dura Ace di2.
I think current trends in simpler bikes with cleaner lines might help popularize (thus bringing the price down) wide-range internal gear hubs like the Rohloff hub.
On my wish list would be more focus on comfort (consider the timelessness of the Brooks saddle combined with newer materials/design) and reliability (could we get puncture-resistant tires that don't have so much rolling resistance please?). Too much focus is currently on weight and aerodynamics -- which makes sense given that pro racing typically drives innovation, but doesn't help the average cyclist much.
There is a drive shaft bike available. Heck there is even a Wikipedia entry on it.
I have never tried riding one. But the thing about bicycles is they are pretty darn good, as currently designed. Brake innovations have come and gone (things like disc brakes on MTB's).
I am sure there are more.
Belt-drive is on the rise. Supposedly much quieter than a chain, and no lube...
Here you can read about the evolution of the bicycle helmets. This does not really look like "they are the same as 25 years ago", including materials, construction, minor things like straps, fancy features like lights, and they are even easier to recycle now.
While the helmets do not look very different from the side, it may matter how well do they work.
What I really fear is strong-hybrid bikes. Not hybrid as in a normal bike, but an electric bike with pedals, but the pedals are only connected to a generator. Pedal when you want, how much you like. It doesn't matter so long as you have enough juice left. That's going to change the feel of cycling much more than current electric bikes do.
I've had the same niggling feeling myself, yes our bike lights are better than 20 years ago and the frame is a 'nicer' type of aluminium but that's not much. A cross over vehicle that takes the best from the HPV world and the best from the cycling world would rock. The role of the UCI in restricting aerodynamic innovation is probably to blame.
Many improvements already exist:
Moreover, many equipments are available today that didn't exist 25 years ago, especially for carrying things and people.
How many of us have friends who struggled with shifting a double or triple crank? Perhaps they just left their crankset in one gear all the time and kept riding? Or perhaps they were intimidated by all that stuff and never got into riding?
It's possible that 1x drivetrains with a usable number of gears should be considered to be a meaningful innovation for casual users. All you have to learn to do is operate the rear shifter. If and when you want a more serious bike for most road and some gravel purposes, you'd progress to a 2x drivetrain later. Of course, it's possible that you will have electronic shifting and you won't need to progress per se, but the shifting system will handle it for you.
In part, this answer is inspired by Shimano's new CUES drivetrain, which unifies their lower-end drivetrains. It has 9, 10, 11 speed options at the rear and it comes in 1x or 2x. The alleged retail pricing seems reasonable to me.