The news that Celtic had secured the services of club captain Scott Brown for another two years was welcomed by the majority of the supporters.

The club legend’s form since the turn of the year suggests he still has a lot to offer on the pitch.

While Brown was rightly criticised after the 1-0 loss to Rangers, the claims of his imminent decline have not for the first time, proved to be premature. However, with Brown turning 34 in the summer, it is fair to say he is coming into the twilight of his Celtic career and the board must be considering a long-term replacement.

A quick look across the rest of the squad and it becomes apparent that even with Brown’s services secured, the squad could look a lot lighter at the end of the season.

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Firstly, the players we know who will definitely not be Celtic players at the end of the season. Timothy Weah, Oliver Burke, Jeremy Toljan and Filip Benkovic are all currently on loan and as it stands are expected to re-join their parent club in the summer.

It remains to be seen whether or not Celtic can secure the services of any of these players for next season. The £15 million paid for Burke and the £13 million paid for Benkovic by their respective clubs suggest permanent moves for either of these players are unlikely. Further loan deals for these players seem to be the most realistic option at this moment in time.

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Celtic also possess a full back five who are out of contract in the summer. De Vries, Gamboa, Izaguirre, Lustig and Boyata are all out of contract in the summer and as it stands, no deals seem to be on the cards.

Boyata, who controversially tried to engineer a move away from the club at the start of the season, could walk away for nothing and seal his apparently desired switch down south.

Gamboa and Lustig have both found themselves the subject of criticism from the Celtic support and neither seem like the long-term solution for the right back position. If no deals are forthcoming for either player and with Toljan’s loan deal expiring, Celtic will only have one recognised right back in the form of youngster Anthony Ralston.

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On the other side, Izaguirre has also been subject to criticism from the Celtic support and when he picked up an injury in the last game and Hayes had to fill in at left back, it exposed another frailty in Celtic’s defence when Tierney is not available.

In the centre, if Benkovic and Boyata do go, it leaves the injury-prone Simunovic and the inexperienced pair of Ajer and Hendry as first choice centre-backs.

Then there are the squad players who seem to be surplus to requirements. Compper, Kouassi, Allan, Benyu and Hayes have not done enough to suggest that they are going to make the breakthrough into the first team, and we could see some of them leaving in the summer.

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Celtic’s business model over the last few years also leave open the possibility that if the right bid is received, then a player will be sold. The most likely candidate would be Ntcham, who has admittedly just signed a four-year deal but has been the consistent subject of interest from Porto. If Celtic received a bid similar to or above the rumoured price of £14 million, it is hard to envisage Celtic rejecting an offer like that.

With Celtic currently sitting six points clear at the top and on course for the “Treble Treble”, as well as finding themselves in Europe after Christmas on the surface it may not seem like investment is urgently required and indeed with the best squad in the country, there is absolutely no need to panic.

However, with the number of players potentially leaving the club in the summer and with the supporters clamouring for 10 in a row as well as a decent crack at the Champions League, investment in the squad will be needed to achieve these targets.

Do Celtic need to invest heavily in the summer?