Rangers dominated the league to win the title by a massive margin of 25 points, with Celtic failing to achieve their dream of lifting a tenth league title in a row this term.
While the Gers are planning ahead under Steven Gerrard, Celtic are yet to appoint a new manager and are just weeks away from returning to pre-season in the summer.
Hartson stressed that the Celtic fans will want a strong reaction next season but insisted that the club are now staring at a massive overhaul in the coming weeks.
The former Bhoy pointed out that there is a massive amount of work to be done at Parkhead this summer and he is still not sure what roadmap Celtic are set to follow.
He conceded that Rangers have emerged as the team to beat in Glasgow while surpassing Celtic.
Asked if Celtic can come back next season, Hartson said on the Go Radio Football Show: “The supporters will want a big reaction.
“For a huge global club like Celtic that is far too many points to lose the league by. We have gone over it several times.
“Rangers had the league wrapped up in November-December time for me when they were 14 or 15 points clear.
“They weren’t going to lose five or six games at the back end of the season even though Celtic had opportunities in the two league games to catch up.
“But it is going to take a big job.”
“What is the plan? Can they claw back the title? It is going to take a massive overhaul of players and staff, a new manager is needed and a lot of work to be done.
“Listen there is a lot of work to be done and I am concerned that Rangers might just be the team to beat now in Glasgow.”
Celtic are still waiting to appoint a new manager with Eddie Howe expected to take charge of the club.
