yes, although nothing is in stone the hibernate and sleep mode will most likely be incorporated. by the time 2.5 is started ACPI will have already replaced APM in most systems. This should make supported systems the rule and not the rare exception they are today.

http://content.techweb.com/wire/story/TWB2001040 4S 0002

Here is a great article from the summit for more 2.5 info
http://lwn.net/2001/features/KernelSummit/