Barcelona will be champions this season under Xavi. I think Real Madrid will not be able to continue this race steadily. They are a team dependent on Benzema.
How can you be so sure Real Madrid can't continue the race to overtake Barcelona in the race for the La Liga title. Real is only three points behind Barcelona, while La Liga still has many games left. During that period anything can happen, Barcelona could lose points and Real Madrid will try to crawl up to first place.
Barcelona has grown for the better compared to the previous season, but you shouldn't assume Real Madrid ran out of gas before reaching the finish line. Ancelotti is very ambitious to defend the La Liga title, he has a good squad to give competition to Barcelona.