You should not need to replace headphones every year or two when they work well enough already.
Nobody needs that and nobody is asking to make changes to the driver and audio quality, that's absolutely fine.
Yet Airpods are bought for the Apple tech like the Spatial Audio and what's pretty much the best transparency mode of any headphone. I have wired headphones for half the price that sound better and if I just need wireless and ANC I can get the popular Sony's for half the price. I own the Max though, I prefer them and I didn't mind the extra cost. Especially on prime day recently that was a decent deal.
Apple switching out the H1 for the H2 that all other Airpods have shouldn't be something to argue about as it merely brings the Max model up to date. H2 improves ANC and the Max have mediocre ANC - I know because I have them and use them daily. That on its own justifies updating the model... and Apple did update it, so it's infuriating they didn't bother to put a newer chip in that's 2 years old now.
We're not asking for anything cutting-edge that would be hard to achieve and costly for Apple to manufacture. Keep in mind the Max are the most expensive over-the-head bluetooth headphones on the market and aren't some budget option. The new USB-C ones aren't selling at prime day pricing either but at full Apple suggested pricing.
every year or two when they work well enough already.
Oh and by the way the Max have a factory defect where the flex cable connecting the two sides breaks after a few years. They all have that and especially if you turn the cups flat a lot (around the neck or using the included case) they'll die after a year or two. So they do not work well enough already by your own metrics either.
They can do zero latency (24/48) lossless when wired.
...if the USB-C ones even still have the wired mode. I presume they will but as that wired mode was never mentioned in specs I wouldn't be surprised if Apple quietly dropped it. Not that this would be an issue either as most people don't buy wireless headphones just to plug them in and the lightning cable was trash quality regardless. At least I haven't tried it out once and why would I need to?
As mentioned, audio quality is not an issue with the Max, there is no need for special wired or lossless modes. The limit is the closed back form factor, it's within the drivers and within the recording quality. There's no issue with bitrate or compression at least if you use them with Apple devices.
it's the casual music consumer / gadget market who obviously have an attention span shorter than release schedules.
Anyone I know who bought them as well as myself got them because they're the final headphone for a while. There is very little to complain about (as long as they don't break down). As such I am not interested in buying the USB-C ones even if they did have the H2 chip. But once mine break down again inevitably and for anyone buying their first pair Apple should offer an up-to-date model.
Adding USB-C is enough of a convenient improvement IMHO until they unveil a V2 model with significant enough differences to warrant an upgrade cycle.
USB-C is the bare minimum nowadays. Calling that an improvement is technically true but it's really just the bare minimum. Nobody releases new products now that have Lightning or micro USB. If anything, Apple's late to the USB-C party with the Max.
What are we waiting for then with the V2 model? What significant differences are you expecting? They only got the most comfortable headband on the market, the best replaceable magnetic cushions, a timeless design, the housing is of great quality, the sound quality leaves nothing to be desired either (it's really good for a closed back, people make comparisons to open back wired ones most of the time, closed back wired ones for the same money sound worse).
(Any changes to comfort/ergonomics would be subjective, for me the Max are the only headphones I can wear for 12+ hours nonstop without issues. So if they were to change that it wouldn't be an improvement.)
Are any headphones able to easily switch between three units?
Any that support bluetooth multi point, which is many but not all of them. It's actually better than what Apple did as Airpods are not truly multi point and need a moment to switch connections from one Apple device to the next. Even though it is usually automatic it's slower. Multi point headphones can switch instantly as they stay connected to all devices at once. Stay away from headphones that do not have that as it will be painful to connect them to the right device.