Yesterday we had a "you had better sit down" moment with the rumors coming off of Warseer. 9th edition is changing, and the Endtimes are the catalyst for these changes in the background and future of the game. However, its not just the background that is changing, releases and how they come about are about to be changed. Armies from 8th edition, from the Endtimes, and future releases, will all be valid, leaving no one out.

As always these are still considered rumors. The source is stepping in to reveal some insight to the new changes that are coming, to help alleviate and correct some misconceptions with yesterdays rumors about the massive changes coming to 9th edition Warhammer Fantasy.

Take your time with these, as there is a lot to absorb. I also want to thank the source for stepping in here.

via a very solid source on Faeit 212
Let me give you some confirmation:
The setting is being completely overhauled - true.
The concept of a huge chunks of the world in a sea similar to the warp from 40k - true.
Faction reduction to 6 - true

As for how it interacts with the current rules.
9th edition takes place after the sundering that brought about from the End Times.

So for the purposes of compatibility, you can use your 8th edition hardback book, representing a section of the culture that hasn't been horrifically changed by the End Times (Recognizing it will have the same drawbacks of using a dated book that are experienced elsewhere).

You can use End Times rules/concepts, representing a section that is still being torn apart.

You can use the new, post-end times rules to represent what is "current."

All the books (again, with the caveat that older books may not be optimal for the new core rules [but truthfully the core rules aren't changing wildly, like 5th to 6th edition 40k, really more of a tidied up 8th edition with a brand new setting]) are designed to be compatible.

Support will be towards the new book, new setting, however, with End Times being in the past.  Viable, but not current.

Expect armies to have fewer units in their core books, which will be heavily focused on the fluff for where they are now, what they've been doing in the centuries immediately following the sundering.  This will create a more "balanced" pool as they will be rapidly produced and released (consider a scale even somewhat faster than what we've had for 40k these past few years).

These will then be expanded on with supplements, not intended as money-grabs (as I am sure they will be received by the majority of your readers), but more as guided hands to acknowledge deficiencies in books, or even "global meta" changes.  The first time that Games Workshop will be openly acknowledging things that need changes.

These units will typically get white dwarf rules treatments heralding the release in hardback of all of the new units from the previous month(s), for a new setting expansion, which will pit several of the races together (representing a collision).

As these expansions are not permanent in the world, so too will these models not be.  They are intended to only get one template injection mold life-run, the same as the books will be printed only once in hardback, then delayed paperback.

They will of course remain legal throughout all of 9th, they will just be more limited eventually, the same as the end time models will not be available forever, the same as XYZ model is no longer available (just with a shorter life span than previous experienced).  I mean... you can't get albion models anymore either, but that campaign was before people whined on the internet, so I guess that's why no one's complaining.

This will allow for more new models, as contrary to common belief, the storage and rejuvenation of these templates takes a lot of resources which can be instead dedicated to new ones.

On the topic of round bases.  The latest version I saw used round bases, but units had the option of ranking up to receive the typical bonuses.  To rank up using round bases, it is intended to use new movement trays which have circular cuts to hold the bases of the appropriate size.

Nothing stops you from (and in many ways you are encouraged to) maintain unit formation the entire game.  But you don't have to.  Note that throughout all of Warhammer Fantasy, changing width/depth was an option, it's just rarely seen.

So to summarize - you can skirmish, but it's in your interests to rank up for different reasons, like shield walling before a charge for instance.  You can alternatively always hold a formation and move the way we're all used to.

----

This will be a very big change.  It is not because GW doesn't care about its old players and just wants to attract new ones.  It is not to fill a void that will come from the fading of Lord of the Rings (which will remain in stores and be supported for a long time due to the agreement with New Line Cinemas).

It is just a very fresh look at a game that hasn't changed dramatically in how it's played since the dawn of the game and company.  It will give everyone the opportunity and hopefully inspiration to do something new, but without invalidating everything from the past.  It is opening room for creativity, not closing doors.

Yes, army books will eventually feel too out of date to play, but that's the same with any new edition.  And new Army Books will typically allow people to recreate what they're "used to" it just might not be the most effective thing they could do with their new book.

The new faction are basically the opposite of warriors of chaos, but good the way chaos marines are the opposite of space marines but evil (in terms of broad tropes, I really hope this doesn't spawn some kind of debate about the morality of space marines).

Lastly, nothing stops you from just playing 8th, and ignoring 9th the same way some people ignore End Times.  Just understand that unlike Storm of Chaos which was post-production looked at as an "alternate timeline" where the clock was turned back to right before it took place for the purposes of the setting, the End Times are real, and 9th will begin where it left off.