I agree with what **rdos** said here, ACPI is actually very useful if you want to build an OS that works on Modern Hardware, especially laptops since you will need Power Management to minimize battery consumption or the battery will drain very fast.
However, I don't really know why there is broken PC,AML,USB implementations, this seems quite illogic. Do you think that Windows or Linux will keep checking for the Interrupt Status of a device each ms ? This is inefficient.
I don't find AML a very huge machine language, anyone can create a parser within a few weeks and often update it for more features and better error checking.
I don't really think that the ACPI will be superseded for now nor for 10 years later, I don't seem to need something more than ACPI however we always doesn't know, I've seen forums from 2003 that predicted what is going now (x64, uefi...)
I'm going to stick with my integrated hand-written ACPI driver, I always beleive that integrating a library will make my kernel much slower.
I don't think a modern kernel will be very backward compatible, just a 64 bit kernel with APIC and ACPI requirements and maybe TPM also.
No one has answered my questions about Page/Swap/RAM files, you can find the topic in the forums main page