Intel Planning To End Legacy BIOS Support By 2020
Making rounds this weekend is a slide deck from the recent UEFI Plugfest. Brian Richardson of Intel talked about the "last mile" barriers to removing legacy BIOS support from systems.
By 2020, they will be supporting no less than UEFI Class 3, which means only UEFI support and no more legacy BIOS or CSM compatibility support mode. But that's not going to force on UEFI Secure Boot unconditionally: Secure Boot enabled is considered UEFI Class 3+.
Intel hasn't removed legacy BIOS / CSM support yet due to many customers' software packages still relying upon legacy BIOS, among other reasons. Removing the legacy BIOS support will mitigate some security risks, needs less validation by vendors, allows for supporting more modern technologies, etc.
By 2020 they are said to be "removing legacy BIOS support from client and data center platforms." Based on the timing, it's then looking like for Intel Tiger Lake or Sapphire Rapids where they may cut off the legacy BIOS support.
More details via this slide deck.