It could. Personally I tend to think it won't happen.

They already said they'll start getting into AFFC/ADWD portions next season for some arcs, for other arcs it won't reach that point before season 5. How fast they'll get through the remaining material after ASOS depends a great deal on what they decide to keep and what they decide to shorten, tell differently or cut from now on.

They've talked of doing it all in 8 seasons, another producer spoke of a minimum of seven, and that they were starting to look at that in their planning of season 4.

I think the talks about Martin having provided an outline while no doubt true are also part of a PR attempt to limit the talks and fears that the TV show might never get an ending or will run into problems as it catches up to Martin. If follows the same logic of announcing with fanfare the series is renewed for a season as early as after the season premiere.

But a very great deal of water will run under the bridge before they need to worry about WoW, let alone about DoS.. so for now... they just don't really worry about this (beyond having everyone's lawyers negotiate all this in the deal for the rights).

The truth is that if they catch up to Martin, they'll need to write a final season with whatever, by their contract, he's supposed to provide them in such case. They can delay broadcast (even skip a year if they must), but they can't halt the production of a show like this, not unless they're willing to invest a whole lot of money to start the machine again.

Martin seems quite zen about the possibility the TV show "spoils" all the secrets of his ending before he releases it himself. It's a bit fishy. I suspect there is a lot of details of the deal between him and the TV show we don't know about and the "he provided an outline for us to use to end the series if he doesn't finish in time, or if he dies" is the official and very simplified version. I suspect by contract they'll get nothing but that outline from Martin unless the book is out or unless HBO agrees to delay broadcast until it's published (with a time limit in the contract, no doubt), in which case Martin would provide them with the draft of DOS, additional help etc.

One thing to remember is that they don't need the finalized DOS to adapt it, not even close to that if Martin keeps collaborating, and when they start adapting it Martin has almost two years left to publish the book before they broadcast it, and that's if HBO doesn't push it to the next fall or something. The best case scenario for everybody (publisher and HBO, that is) would be that Dream of Spring is released a few weeks before the last season of GOT gets on the air.

There are rumors of prequels that could eventually fill the wait for the last season of GOT (though I've no idea if they plan to wait that long for that project or if it's something they plan to put on the air earlier than that).