Short answer: According to the Articles of Incorporation in Macomb,  according to Section 8, the authority (and presumably their authority to tax) is dissolved by a decision of the board.

Interestingly enough, the County Board approved PA 296 of both 2012, and 2010.

Not sure if anything can be done with that?

In Oakland, you'll need to abolish PA 296 to accomplish this.

In Wayne, I wasn't able to find any record of their articles of incorporation.

It would take much to have a forward thinking official looking out for the best interest of Michigan Taxpayers to put a bill in the hopper stating this:

"The People of the State of Michigan enact Public Act 296 of 2010 in hereby abolished."