I think that the character of Pierce has run its course, but I don't like the idea of the character having to leave because of this
No matter who started it, I can't support Dan Harmon's actions at the wrap party. If you've got a problem with someone, the time to make a big deal about it is not in the middle of a party. That's something we all should grow out of by the tie we're 12.
Not saying that walking off the set is a good idea either, but at this point the scales of Right vs. Wrong (granted, I don't know the absolute full story) the "Right" Scales lean in Chevy's direction.
The thing that I wonder about is: would losing Chevy Chase actually increase the shows chances of returning for another season? Studios and networks love to save money and with Jim Rash having been made a full cast member this year and Ken Jeong being aboard, I could see them saying sayonara to Pierce and giving material intended for him to Chang.