My speculation is planned obsolescence, tech companies have long learnt to always keep something back so you more likely to need to upgrade sooner.
The refresh models that come out after 6-12 months, might address some of this stuff.
I believe we're going to start to see a slower rollout cycle, as it's simply too expensive to do a new product every 12 months at the moment and the demand isn't going to be there, as although Alder Lake is a big step forward for Intel, most consumers aren't going to care, due to the lack of GPUs at reasonable prices, plus the fact that all computer parts are more expensive now. This isn't even taking into account that most consumers prefer to buy laptops over desktops.
Then there's the fact that most companies are having issues getting fab space, although this doesn't really affect Intel in the same way.
Time will tell, but I see a change coming industry wide.
Also keep in mind that if you get a DDR5 Z690 board, you could in theory upgrade your CPU, but this isn't likely to be the case with the DDR4 boards.
For those that are interested in even more details, @harukaze5719 has put together an impressive spreadsheet with all of the boards in it.
