Xavi is too loyal to be Barcelona coach and because of that, I think it was the right decision for Xavi to resign. Because anyway, the financial crisis that Barcelona is going through is really having a bad impact on the management of the team and also the performance of the team.
I think the main reason Xavi resigned is because of the pressure that he is facing as Barcelona boss, especially from the Spanish media and journalists, Xavi has had problems with the press since he became manager and i believe he could not take it anymore. Barca's financial problems also contributed to the Spaniard leaving, but i don't believe that is the main reason he is leaving the club. Barcelona must look for a new manager now, with their limited funds. There is no speculation for now on who will take over from Xavi, but the person is going to have a huge job to do.
This might still be a strategy to get him resigned, However, Is good thing that he resigned the job than to get sacked by the Barcelona management board ,However, in my opinion Xavi stay at Barcelona hasn't yielded much result so far, that is in trying to bring back Barcelona to its usual glory, therefore it is right time they give another manager chance to try to fix things up in Barcelona