It will ultimately come down to money.
If Santander threaten to pull out theirs if either of the Spanish GP's are axed Mr Ecclestone won't be amused. Turkey and Canada have given us the most exciting dry races so far this year but action on track is not enough to save them.
Personally I think there is room for all of the new tracks but not all in the same season at once.
There needs to be a core set of tracks which feature every season;
Silverstone, Monaco, Spa, Monza, Hungaroring, Interlagos, Gilles Villeneuve, Melbourne, Rome, Sepang, Singapore and Suzuka.
The additional slots will then be taken up by tracks on rotation;
Valencia/Barcelona, Hockenheim/Nurburgring, India/South Korea, China/Russia, Abu Dhabi/Bahrain, Austin/USA 2 and Turkey/Bulgaria.
That will give us 19 races per season and enough variety to keep the fans and sponsors happy. This will also allow for flexibility should any of the tracks decide they cannot afford to run GP's.