Xavi is doing his great job and the El Classico with Real Madrid shows that Barcelona still can play at top level in their best matches. Nevertheless, they must maintain it in more matches because net result is better than one sudden excellent match among bunches of bad matches.
You are right. Xavi's main goal now is to qualify for the Champions League. If they fail to do so then next season we will see a weak Barcelona team again. Xavi is now looking to form a team of young dependents. If he succeeds, Barcelona will be strong again in the next few seasons. Barcelona now rely on two young players, Torres and Fati. Moreover, the number of young players is more than the number of experienced players in midfield and forward. Xavi will now strengthen his defense and midfield. Only then can Barcelona be a stable team.