As a Madrid fan, I wouldn't overestimate whether Madrid could improve after recruiting several new players and bringing in a top-tier coach. I'm not underestimating Madrid or Alonso, but I simply hope Madrid can pursue more prestigious titles like the Champions League. Even if Madrid fails to win La Liga, at least Alonso's team managed to lift the Champions League trophy this season, which is a more valuable trophy. Still, Madrid's improved performance will make them better prepared to compete with Barcelona, and La Liga will become more competitive.
Real Madrid are going try this season than next but you see current form of Barcelona, those guys are going to take more time before they come back again maybe next season. The only rival and problem of Real Madrid is Barcelona and while the two teams are very active good performance, one is very ahead of the other except that there is something Xabi is going to brings to the table that the club hasn't seen yet and can push Barcelona down on the table.
Another thing we should be looking is how other teams respond to the Champions League also matter. Manchester City are there warming up and PSG is another team that has been on fire since last season. PSG might not be able to win Champions league this season but Barcelona will not take their eyes off the trophy. If Real Madrid want to win this season, honestly now it's the time. Xabi just need to push this team to do it and then that will be all, even next season Barcelona is going to be terrified.