Every two years or so Intel releases a new CPU socket that prevents existing motherboards from using new CPUs. This is not entirely a bad thing because progress marches on and support for legacy parts cannot continue for long periods of time. Because Z390 boards will likely cease production in a couple of months, new users wishing to duplicate this build will probably look to the Z490 successor. So this build guide will adapt accordingly, but support for Z390 Designare will continue. So no worries there.
I'm not sure whether I'll personally upgrade to Z490 -- at this time the value proposition for me is just not there. Have you seen the suggested pricing on Z490? The Vision D might be US$393 versus US$269, which is a 46% increase in price. But most of all, the performance of my two Z390 systems is already more than I need.
Agreed, especially on the laptop side. I have not considered building a laptop Hackintosh simply because Apple has so many excellent choices at different price points. My 2012 MacBook Air is still going strong, but the new rumored 14" MacBook Pro is calling my name!