Buying him back would be welcomed by the vast majority of fans, because few - if any - wanted him to leave in the first place.
Neil Lennon was among those who wanted Gary to stay and did all he could to persuade the club to meet his increased wage demands and sign a new contract.
But it never happened. And, I reckon it will be the same outcome with regard to Gary's return to Paradise, even though Norwich are virtually relegated and his dream of playing in the Premier League has lasted just one season.
I know Neil has not closed the door to making a bid for Gary, but I reckon there are too many obstacles in the way for this to be a goer.
First of all, there's the financial barrier.
Celtic would not pay the money it would have taken to keep Gary here, and I really can't see him taking a pay cut to return.
The transfer fee would be another problem. He moved to Carrow Road for £5.5million, but that was because he had only a year left on his contract.
By contrast, he is only one year into his deal at Norwich, so the price tag will be significantly more.
Secondly, Gary wanted to try playing in the top division in England, and has now had a taste of it.
His performances will have brought him to the attention of a number of clubs and, if Norwich show any inclination to let him move out, there would be no shortage of offers from clubs willing to keep him down south.
Thirdly, and perhaps most important of all, Gary is not the kind of striker Neil is currently looking for.
He has brought in Leigh Griffiths, Kris Commons has stepped up to the plate to get the volume of goals required by the team and Anthony Stokes has also upped his strike rate.
When Neil brought in Amido Balde last summer, it was an indicator he wanted to find a striker who could offer a physical presence up front on his own, especially in big European matches.
The big man has not proved to be the answer, but Neil is still talking about searching for that type of player.
For all Gary's attributes, he doesn't fit this particular bill.
Now, we have learned never to say never in this game, but I would have to say the probability is we will not be seeing Gary leading the line for the Hoops again any time soon.
It can often be the case players have to move from Celtic to appreciate what a special club it is.
But I don't think that pertains to Gary because he always seemed to enjoy the opportunity given to him by Celtic, and the adulation he got from the fans for the goals he scored.
I am not against players returning to the club. I never brought anyone back to any team I managed, but I know that it can work.
For the perfect example, I always refer people to Bertie Auld who was brought home from Birmingham.
And, in his second spell in the Hoops, Bertie went on to become one of the finest midfielders the club has ever had.
Neil will already have a number of potential signing targets in his sights.
It is not just up front he wants to strengthen, of course, and the name Robert Snodgrass continues to be linked with the club.
Now that Norwich's fate appears to be sealed, the indictions are that this is a transfer which Celtic could attempt to complete quickly.
A possible hold up might be the fact the Canaries are currently running with an interim manager, and might want to wait until a permanent appointment is made before allowing anyone to leave.
Robert has never hidden his love for Celtic, something he reiterated when he was back in the city recently.
And, if reports his family wants to move back to Glasgow are true, agreeing personal terms with him might not be a problem. The fact he is also entering his final year of his contract is also in Celtic's favour. But, again, I don't think they would be the only club in for him.
The thing we can say with certainty is there will be comings and goings this summer, though Neil has made it clear he wants it to be a bit quieter than last year.
He accepts he can't control everything that will happen. So much depends on what offers come in for which players.
Neil already knows he is losing Johan Mjallby after four years by his side at the club.
Johan has been careful to leave on good terms, and it was no surprise to hear he would not object to a return one day.
Could that be as manager? That's a tough one to answer. It would all depend on circumstances, opportunity and what he achieves in whatever he does in the future.
Certainly, the role he has performed as assistant manager has done him no harm.
But not everyone is cut out to be a manager. Some are naturally a better fit as a No.2.
What is most important is you get the chance to develop before you take the big plunge.
My knee injury meant I moved into coaching youths at Chelsea when still in my twenties. I then got the call to become assistant to Ally MacLeod at Motherwell then stepped up to become a boss for the first time.
I got the chance to manage Celtic when I was still only 35, and always maintain it was too soon. I was better equipped to do the job when they removed me from the position.
I had other management jobs, some as assistant. But I always knew I needed to be a manager, not a No.2, and Johan might feel the same once he has been his own man.