Today, at the June 2021 WWDC event, Apple announced macOS 12, named Monterey. 1st developper's beta was released for download thereafter. 1st public beta will follow in July with 1st general release in the fall as usual.
More details on Apple's web site:
On the supported platforms front, it looks like Monterey drops support for many Haswell-based iMac/MacBook Pro/MacBook Air models with support starting at 2015 Broadwell models. But the Mac mini from Late-2014 and MacBook Pro from mid-2015 appear to remain supported and, with it, support for Haswell graphics. Probably just because these 2 models were sold until Q4 and Q3 2018.
So, support starts at the following models:
iMac 16,1 (Broadwell with iGPU graphics) Mac mini 7,1 (Haswell with iGPU graphics) MacBook 9,1 (Skylake with iGPU graphics) MacBook Air 7,x (Broadwell with iGPU graphics) MacBook Pro 11,4 (Haswell with iGPU graphics + Kepler dGPU)
This time -and as could be expected-, support for HD4000 is definitely dropped and no Capri framebuffer is provided. We'll probably see rapidly if this can be as easily patched as per support for, say, Intel HD3000 and nVidia Tesla graphics in Mojave/Catalina.
Support for nVidia Kepler remains present (Geforce + NVDA kexts still provided), so no apparent change on that front.