Expectations are relative to the talent we have.
When we have a title capable squad, our expectations are for titles.
You could include the Green Bay Packers, Montreal Canadiens, Notre Dame football and maybe the Yankees in this discussion as well.
After Russell and Sam retired, we expected some down years to rebuild, same with the Cowens, Hondo and Jo-Jo team and then Bird's crew, though Red had set them up for continued success until the losses of Bias and Lewis. So, Celtic fans have been patient during rebuilding years and have expected success as the talent level was raised again thru the draft and trades. Red was a genius. Imagine what he would do with this situation and it wouldn't be walking around on eggshells trying not to hurt anyone's feelings.
No one has expected a repeat of the 50-60's run of titles. But the team has been rebuilt since the Garnett/Pierce trade and had plenty of time and experience to now be championship-ready. But there are specific problems that everyone can see and that can be fixed
with competent management. Current ownership and Brad Stevens are throwing away this opportunity.