In my view Leciester is surely going to be in top four in place of Arsenal or Chelsea...
If they continue playing the way they have been playing, then they will probably finish in the top four, the real question is, can they maintain this standard of theirs till the final week of the season? If they fail to do so, then I think the best they'll get is a Europa league spot. But if they finish the year in the top four, then that's enough reason to believe they will make it to the Champions League next season.
Chelsea and Arsenal both have very terrible time so its going to hurt them.
Chelsea aren't having any terrible time in the league this season, they are even title contenders, and if they beat Manchester City next week, then they will be making a big statement, for Arsenal, yes they are indeed having a bad season.