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.
Difference between Real Madrid and Barcelona are only three points that are not too big. One match can equalize this difference for Real Madrid so the chance for Los Blancos is not small.
Latest matches, Benzema has been playing so good and he is showing that he does not have worse performance after getting his first Ballon d'Or. He got more injuries in this season but whenever he was available for playing, he played very well. With his experience and outstanding finishing skills, I am sure Real Madrid and Ancelotti will get benefit of his better fitness in rest of season.
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.
Barcelona are better than themselves in the last season but they are not better than Real Madrid. We have to wait till season ending to say it, for now it is too soon to conclude. Personally Barcelona and Real Madrid are not different in quality and if I choose a better team, I choose Real Madrid, not Barcelona.
Of course Barcelona have good future with their young players but now they are not better than Real Madrid which have better combination of young and old players. Carlo Ancelotti is a more experienced and better coach than Xavi.