[…] and move to uefi only supported boot which
has been available on any common intel based x86 platform since atleast
2005.
(U)EFI was not available for the general market in 2005 (except on Apple devices maybe).
It was introduced around 2011.
I own 2 devices which are booting with non-(U)EFI BIOS. One is too old, manufactured
around 2010 when (U)EFI was not available. One is new enough to having (U)EFI, but
it's a mess and never worked with Fedora's (U)EFI integration so I was forced to
install it in legacy BIOS mode.
In other words: I think it is too early to drop non-(U)EFI BIOS support.