If the manufacturers actually want to sell more devices, I have a free idea for them. Lower the prices. The manufacturers already have admitted that the flagship phones cost so much just because they can get people to pay that much. Yet at the same time they complain about stagnant market. How dumb are they if they cannot connect the dots?
Also, if they just sell the same product with slightly tweaked exterior and a couple of additional software features, and have slightly faster CPU that is slowed down to the same speed by more bloatware, and the same goes for the battery (larger capacity, same battery life) who is interested in upgrading?
Though it is better for the environment I guess. I slowly went from upgrading once per year to having the same phone 5 years (and counting), just needs an occasional battert swap. And fortunately we will soon go back to user-swappable batteries, making that even cheaper and even less of a hassle.
There was a major turning point in the health of most countries already in 2020. The C-word. The thing that turned life expectancy down in almost all countries (somewhere sooner, somewhere a couple of years later). The thing that doesn't become the F-word no matter how many times you repeat it. The thing that increases your risk to Alzheimer's disease, dementia, diabetes, heart attack, Parkinson's, you name it, by tens of percents. Yeah, it's COVID, and it is not "just" a flu. And even the flu is not that benign.
Infectious diseases are one of the biggest health burdens to society even as such, even without their long term complications. The most frequent ones spread through air. And we do not need CRISPR, AI, quantum computing, wonder pills, individual genomic sequencing or anything like that to massively reduce them. We need air hygiene. We need ventilation and air purifiers (I'm an advocate of respirators, too, but we can improve greatly even without them). Microbe-free air can bring just as big health revolution as microbe-free drinking water has brought. But it is ironic that governments are spending billions on clean drinking water campaigns abroad, and don't do almost anything on clean breathing air campaigns domestically. Yet we end up paying much more for the consequences, and not all of the harm can be undone with any amount of money.
So what is the theoretical limit of battery energy density? I'm not talking about just lithium ion batteries, but any batteries.
However, not being able get to places quickly enough is not really any of the main challenges of the humanity. The biggest issue is climate change, and at the moment any usage of biofuel cannot be offset by more biofuel production. So unless we at some point achieve abundance of biofuel, then the supersonic jets might be a good thing. Until then, they are mostly a bad thing on the bigger picture.
Not the first time people invent something great only to figure out way too late that when solving a problem, we greated a bigger problem. Lead added to gasoline prevented engine knocking, but polluted the environment. Arsenic in wallpapers helped to make a vivid green color, but was toxic. Asbestos was great for many things, including causing lung cancer. Cadmium made nice red color to plastic dishes, but was not equally nice to your body. Fossil fuels helped humanity to gain so much, but are also helping the Earth gain excess temperatures. PFAS are wonderful for so many uses, but the opposite goes for the environment. The list is endless.
The sad thing is, for most of these, we knew way before stopping about the harms, but the good old normalcy bias in us first needs to really see the negative consequences with our own eyes before taking any action. We are now repeating this with microplastics. We should really stop using plastic where reasonably good alternatives exist, invent new alternatives, reuse and prevent plastic going to the environment.
Where there's a will, there's a relative.