I think the show, if filmed out entirely, would last 9 seasons. That gives GRRM a little less than 6 years to finish the last two books. If he's truly going to get in done in 7 books and beat the show to the punch Winds will release no later than the beginning of 2015, with Dreams coming 4 years later at the beginning of 2019.
This is what I think...they are probably going to combine books 4+ 5 into 3 seasons. Cut tons of the fat off, and I'm going to "generously" assume that the last 2 books get 2 seasons each. this will give us something like this:
4 - 2013 - FILMING 2/2 SOS
5 - 2014 - filming 1/3 FFC + DWD
6 - 2015 - filming 2/3 FFC + DWD
7 - 2016 - filming 3/3 FFC + DWD
8 - 2017 - filming 1/2 WoW
9 - 2018 - filming 2/2 Wow
10 - 2019 - filming 1/2 DoS
11 - 2020 - filming 2/2 DoS
That means that by 2016 at the latest, WoW has to be out so that they can start adapting it to film in 2017.
And DoS has to be out by 2018 for the show to start adapting that for TV.
So 5 more years for 2 more books...at the most optimistic. He's not going to make it.