After listing and reading this
Globalnews - Burnaby’s Derek Corrigan named mayors’ council chair it seems to be that the other mayors didn't want the two cities that will receiving dollar billion projects also the ones heading up the council.
One sticking point seems to be the Broadway Subway project, if the engineers come back and say that it can be done above ground then they want Vancouver to pay the difference to make it a subway. Coquitlam had wanted the evergreen line to be partially a subway but that was reject and Coquitlam didn't have the money to cover the shortfall.
Votes are still weighted, eg Vancouver has the most votes, followed by Surrey and so on. Council elections are 1 mayor, 1 vote. Seems to me that the mayors are still moving forward with their 10 year plan, this isn't a revolt, they just don't want the ones in the leadership roles to be not the ones receiving the most benefits
I won't be surprised that behind closed doors the mayors knew this was coming. Linda Hepner didn't attempt re-election, and the District of North Vancouver Mayor Richard Walton got the vice chair position.
edit: The cynical person in me thinks that Corrigan will be viewed as fair and balanced as he didn't vote for the 10 year plan so he'll be able to sell it better than any other mayor.