Originally Posted by tcs

A few points, just off the top of my head here in the USA:

Gravel bikes theoretically have more relaxed geometry and lower bottom brackets than cyclocross bikes, but some models are just remarketed cyclocross or touring machines.
Triple cranks moved to wide step double cranks moved to 'compact' double cranks moved to 1X (single chainring) cranks paired with huge range rear cassettes with 10, 11, 12 and 13 cogs.
You can't swing a cat without hitting a disc brake. Hydraulic actuation is common on the top parts groups, both for disc and caliper brakes.
Go fast machines are incomplete without high profile, aero rims.
Running out of meaningful improvements in the off road world, the powers that be decided to sell everyone a bike with a different tire size. 26" (ISO559) is being supplanted with 29" (ISO622) tires. In reaction, another cult promoted an obscure French tire size, 650B (ISO584) under the marketing name 27.5".
Tubeless tires, both on- and off-road, are gaining traction, if you'll pardon the pun.
'Fat' bikes with 3"~ 4" wide tires are available for mud, sand and snow riding and looking phat.
Carbon fiber is everywhere and less expensive.
Campagnolo has all but disappeared.
Like a lot of brick&mortar retail in the USA, bike shops are on hard times.
Multi-path (direct to consumer) sales is the new retail model.
It can be cheaper to order & ship something from Europe or Asia than buy it Stateside.
Professional, franchised mobile repair shops in the back of vans (like food trucks) aren't uncommon.
As I mentioned, the recumbent world is going trike.
Electric mopeds (a.k.a. 'e-bikes') have been the 'next big thing' in cycling for years. Federalist-system USA has a hodgepodge of state laws preventing a unified market.

You don't need any of that to ride and have fun on your bike.

Oh! Due to on-going improvements in optics, batteries and LEDs, bicycle lights aren't just different, they've actually gotten a lot better. W00T!