Bear in mind that if you are top driver, you can adapt. I know that Button struggles to do this, but I would expect Alonso and Hamilton to make the necessary adjustments. If Hamilton (in particular), is struggling to make his tyres last, he will simply work in an extra pit stop into the strategy and rely on brute speed to win races. Luckily for McLaren/Hamilton, this is an option.
Button has proved this year he LIKES a heavy car and is particularly kind to his tyres - so he shouldnt need to adapt that much.....
Brute speed wont be that much of an option with a number of teams using the same engine (on some tracks thats all its down to and all Merc's where together on the grid)