Different circumstances, but I think back to the 1992 Playoffs when the Celts advanced past Indiana in the first round with Bird out with the bad back that would soon spell the end of his career.
They played Cleveland the next round and took them to a 7th game. Bird came back and struggled through the final four games of that series, but really the team almost looked better without him at that point.
If KG can come back give them what he gave during the 4 game stint he had in April (it was April wasn't it?), then swelly welly, but at this point having a hobbled KG out there may not be the best thing for the team (to say nothing of KG's health moving forward).
People forget how good that 91/92 team was and how deep. Here's their roster:
http://www.basketball-reference.com/teams/BOS/1992.html They finished the season by winning 15 out of 16 and went on to sweep the Pacers in the first round. They were the hottest team in the NBA and even without Bird/an injured bird they took a very good Cavs team to 7 games. Also remember that Dee Brown blew out his knee in preseason (and was never the same). The previous playoffs, Dee Brown was out playing a still in his prime Isiah Thomas. He looked like a star and looked great in preseason too. Without injuries to Bird and Brown, I believe the Celtics would have won the title that yr (and many people call that the best Bulls team of the 6).
The Brown injury really hurt, b/c Shaw/Lewis/Brown was going to be an amazing backcourt. You had Gamble, Bird and Parish up front. And talk about back up bigs. You had McHale, Pinckney and Klein. Rick Fox was a servicable rookie. For some reason, besides Brown never being the same after his injury, Shaw's career started to go down hill this yr and he was traded midseason for Sherman Douglas, but for this yr at least, neither Sherm or the returning dee was the leader at the point. John Bagley was. Injuries are a mofo, b/c that was a deep talented squad. No wonder Stojko O'Bryant didn't get any burn.

oops not trying to hijack, so yeah I hope KG plays. I predict gm 4 versus Cleveland he makes his return.