Would everyone be up for welcoming Ole back 10 years down the line, assuming that he was able to achieve relative success at a smaller club (For example, taking over at a team like Watford and taking them into Europe)?
When he first took over as caretaker manager, not one single soul imagined that he would still be in charge now. However, the run we went on made it almost impossible to not buy into the fact that he might be what we were searching for, as it just seemed to "click". As soon as a little bit of comfort set in and the new managers bounce was gone, performance levels have never been consistently excellent for more than 5 games at a time. What has been proven is that he still has an awful lot to learn, and he will not be afforded the luxury to learn on the job here when our rivals pull further and further away.
But if he can go to another team, develop a style, make poorer players and squads perform better than the sum of their parts, then he builds respect within the game. He can come back to us not as Ole who scored the biggest goal in our history, not as Ole who took on too big a role too soon, but as an ex legend who earned a rightful opportunity to prove himself as an elite coach having proven he can get a system to work at another club.
it's not his fault. You'd have to be an exceptionally pessimistic individual to have not got caught up in the hype when he first started as manager. But the lack of experience of both he and his team has been found out, so let them go and figure out how to be successful elsewhere, and get a proven team in who know how to win.