The official route announcement is on 18th October.
The start is in Liege, Belgium and the second stage starts in Vise, Belgium. It's hard to see that the race would run anti clockwise again, as they would need either some long stages, or long transfers toget down to the Pyrenees by the end of the first week or so.
There are also strong rumors that the tour will visit Switzerland next year, which is logistically difficult if the race runs anti clockwise (it would have to visit Italy again to do this, which would be unlikely given it was there this year).
There is a website called velowire where the blogger does a MASSIVE amount of research into the tour route. Hs accuracy rate is phenomenal.
I think you'd be pretty safe in relying on the race going through the Pyrenees In the last week. If the guy in the above mentioned blog is right, it's hard to see how they I'll use the 'legendary' climbs of the tour next year (Galibier, ADH, Tourmalet).
I went to the tour this year, both in the Pyrenees and the alps. I enjoyed the Pyrenees better. The geography just makes it easier to see the tour on multiple days, as well as getting around the area, especially if you're looking to do some riding as well.
Enjoy it!!, it's an amazing experience!