I will agree with Mike in that the Hills area does not in anyway need a Cedar Point type venue, but it does need a common focal point outside MIS (which only brings people in twice a year). I think MIS is in a perfect location actually and it brings in a boatload of revenue to the region for the minimal amount of impact it creates. Many of the NASCAR venues are "in the middle of nowhere" types. Lenawee County would be in a serious hurt without the track since let's face it... no one is lifting a finger to make ANY effort to bring any type of industrial development here, or even infrastructure for it. Natural beauty will only get you so far... eventually people need to work or they just leave.
As far as the I-73 project that gets brought up about every 3 years... the Lenawee County portion though labeled critical is oversold in terms of its importance. Obtaining the land and finding a really good route would be tough, I think major upgrades to US-223, i.e. taking out all the 90 type curves and making it a 4 lane divided highway in the rural areas with only a few intersections would be just as adequate of an upgrade. History has shown us in Michigan, that the quickest way to kill a small town is to bypass it with an expressway (St. John's anyone?) so I think you just keep traffic flowing right on through Adrian and Blissfield and keep those dollars in Lenawee County.