I think Pochettino will fill the void of players who have left Chelsea in their first-team squad and the most important thing is young players or players who really contribute well so that they don't spend too much money buying expensive players but they don't work well,
I agree with you that Chelsea will reach top 4 next season, because their new coach is still doing some research to ensure he bring new talented players that will help the team to improve higher next season. I don't think pochettino will allow what happened to Chelsea in this season that made Chelsea to finished in 12th position in the premier league table to happen next season than to do everything possible within his skills to make Chelsea fans happy. I believe, the new coach will release some players in this summer, so that he will be able to bring some players that will handle those position more than the old players so that they can break record next season by embracing the title.