Warhammer Fantasy is very widely thought to have a new edition coming sometime next year. Earlier today we had some rumors flowing that were discussing the release of a new edition and what it might look like. A very solid rumor source has also chimed in on exactly what 9th edition will be looking like, if it were to come out.
Please remember that these are rumors
via an anonymous source on Faeit 212
If 9th edition were coming out, it would have the rules for all of the armies found in brief within the Core Rulebook. This would be for a player's reference to know the gist of what they might face against, not so much to make an army list and play from.
That said, if 9th edition were coming out, any army that does not receive a hardback 8th edition rulebook will notice that in the 9th edition core book their rules will be slightly more detailed, including points costs changes and the like; but they would still need their 7th edition arnybook to play in earnest.
Said armies would also be the first to get updated with 9th edition books if the new edition were coming out.
Also, any armybook after and including Lizardmen also is being built with the next edition already in mind, regardless of when 9th is actually going to come out.