What’s your data source?
Keep in mind that the modern, mass middle class was created in the mid-20th century through government policies and post-WWII economic growth.
For example, the vehicle mortality rate is 1.44 per 100 million miles driven. That's down 17% from 2000 (so 25 years ago). However, the change from 1975 to 2000 was 53%. That's because as we get closer to 0, it gets harder and harder to improve those rates. On this metric at least, I don't think another 25 years will result in a noticeable amount of improvement?
In the other direction, some things will become scarcer (and therefore cost more). Real estate is the obvious one; we can't create more land, and we keep having more people. Easily accessible drinking water is another; desalination is getting cheaper, but it's still way more expensive than pumping aquifer water.
And some improvements are necessarily 1 time things. You can get tropical fruits year round, but that's been widely available since the 80-90's from what I can tell. So come 20 years from now, what will people be able to buy in a grocery store that I can't buy right now?
Being able to eat pork without cooking it to death for fear of trichinosis is a recent development.
Also, the old movies where someone tries to commit suicide by sticking their head in an oven. That was coal gas and we don't heat homes with it anymore.
Especially silly that you mention housing because if there's one thing that is absolutely fucked for the middle class of the 2020s is housing.
In every developed country whose numbers I've seen, the size of the average living space is up 30-50% since 50 years ago.