Agree it should ship with 5.8, the problem with shipping with nvidia 440 drivers is the forum may get spammed with posts on how to update to 450. I don’t which will clutter the forum most that or issues with virtualbox (all though it doesn’t seem to be everyone?)
I tried the 20.1-rc5 of Manjaro kde version who have the 450xx series and the 5.8.x kernel on a desktop hardware (Gigabyte motherboard, Intel i5, SSD, Nvidia GTX card, …). I didn’t encounter any problems.
Using the 450 driver since some weeks now and since it’s first release also the 5.8 kernel.
No problems. Even VirtualBox works just fine.
So I see no problem shipping kernel 5.8 with the 450 driver.
Also, even if it has bugs for some users, the 440 driver has other problems like missing features and broken cuda and hardware video encoder.
Guess 450 is the best option