PC BIOS (and CSM-Simulation, in particular the "access for end-users") will be killed off by 2020 (Intel > pure UEFI), but that's not all*.
http://uefi.org/learning_center/presentationsandvideos ("Last Mile" .. by B. Richardson, Intel)
Unterschied UEFI-Firmware Class 2 (mit) und Class 3 (ohne, "pure UEFI", really? or only blocked/disabled?)
CSM supports old HW und modern systems can boot old/other SW. Without it, only UEFI-native hardware and software will work. These Option ROMs are, like the BIOS themselves, written in 16-bit real mode x86 code. boots up acting as if it's a 16-bit 8086 chip and still has all the ancient 16-bit processor modes
http://yarchive.net/comp/linux/efi.html (Linus Torvalds, 2006 about EFI, Relevanz heute?)
P. Bright: UEFI is an open specification and, in theory at least, any developer could write a UEFI firmware, in practice, most UEFI systems use code based on the UEFI reference implementation provided by Intel. This implementation, called TianoCore, is then modified by firmware vendors such as AMI and Phoenix, and subsequently integrated into motherboards by Dell, HP, Lenovo, Asus, and so on

Und hier ist auch was los, sind sich noch nicht alle einig. https://news.ycombinator.com/item?id=15579592

titled “Strategies for Stronger Software SMI Security in UEFI Firmware” .. und .. The Windows 10 Fall Creators Update adds new requirements that include improved support for TPMs (Trusted Platform Modules) and new functionality for Secure Boot BIOS update
requirements that Microsoft mandates in order for a piece of hardware to be qualified for a Windows logo

*TPM goes into UEFI! > was sind die Konsequenzen?
TCG EFI Platform Specification, for TPM Family 1.1 or 1.2, vers. 1.22, Revision 15
PDF Januar 2014
(Schemata/Bilder, Seiten Nr. 10, 12, insb. 13 und 15 etwas beäugen, PCR-Prioritäten?)
TPM (Kritik)
künftige HW-Konsumation? Eines Tages werden sie die HW (PC, Tablete, Smartphone ...) "verschenken", konkret zur Konsumation ausleihen (Besitzer bleiben sie selbst), Hauptsache die Endbenutzer liefern Daten.

Könnte folgendes eine künftige Alternative für Endbenutzer sein (gestaltbar sein)?
(POWER-server, every OPAL POWER machine)
und PowerPC? > mit Skiroot (mit/ohne Skiboot) und Petitboot?
What we all really want though is to run Linux directly on the hardware, which meant a new boot process would have to be thought up ..
Implementation-Einbau von (Kombination) mit GNU/Grub2 (Grub) evtl. un-möglich?
Skiroot itself (not including Skiboot) is roughly comparable to UEFI, or at least much more so than legacy BIOS implementations. But whereas UEFI tends to be a monolithic blob of fairly platform-specific code (in practice), Skiroot is simply a small Linux environment that anyone could put together with Buildroot.