What stuff are you talking about specifically? Modern Campagnolo is still fully rebuildable. The quality on modern Shimano stuff, the highest-end of which are still made in Japan is fantastic aside from some of the carbon cranksets which are known for delaminating (which I'm sure they have fixed since Shimano still to this day honors some warranties from the late 90s). I'd put their current drivetrain offerings way above the stuff they were making in the mid-2000s which felt incredibly flimsy by comparison. SRAM's warranty department is so good that they'll replace parts free of charge and not even request that you return the defective part. These companies have enough to lose that they really don't try to put out absolute disposable trash unless we are talking about the absolute bottom end of the bike segment, and anymore very little of that is made by reputable manufacturers anyway aside from like $4 non-series Shimano derailleurs, which the replacement cost is less than 1/8th the cost of repair even if they were rebuildable. Shimano to this day, even on thru-axle hubs sticks with fully adjustable and rebuildable cup-and-cone style bearings rather than the cartridge bearings most manufacturers have gone to.
Working on these bikes in 30 years will be no different than working on bikes from 1992 in 2022. Unlike cars or motorcycles, there are standards that stick around in the industry. Most bikes STILL use the standard BSA threading for bottom brackets which is over 100 years old now. 9/16" pedal thread is still standard. Cable heads have not changed in decades. Rear axle spacings have varied, but if you can still get S7 size tires in 2022, there's no reason one or two manufacturers won't keep oddball thru-axle threadings and lengths in stock when there will be buyers. Suntour cassettes and accushift parts are the only thing that has gone fully extinct from that era, but any Shimano replacement drivetrain will work way better, even at the low end of the spectrum.
Sounds like just a blanket statement about the current state of "things" like electronics, etc...but it really doesn't apply at all in the bike industry.