I'm seeing references to a 1999 law passed by the State Legislature. Of course, as you said, the legislature can take it away if it wants to, but that would probably require unified government or a veto override.
Wayne County has 840,000 African-Americans so they won't have any trouble keeping 2 VRA districts within county lines. If a legislature tried to override the law this way they'd face a lawsuit alleging packing from the Democrats.
Did you see the results from the 7th district last year? The Democrat was a true fourth-rater, not even a local elected official, but an organic farmer who raised no money. She took 46% in an open seat race against a state senator. I'm trusting the environment will be better next time but this is not a district in which we can pack Democrat-leaning areas like Monroe County and hope to keep an excellent conservative like Tim Walberg in office.
In 2001, the GOP controlled both houses of the legislature and the governorship, which is why the party could push through its partisan redistricting plan. It wouldn't have taken too much additional pushing to also repeal the 1998 law that you mention and make the plan even better for the GOP.
The two black-majority CDs were around 69%-70% black back in 2000, so had the legislature drawn them to be over 65% black (as opposed to 61% black, as they are today) it would have been arguably required by the VRA. Remember, the VRA prohibits retrogression (or whatever it is that they call reducing the ability of minorities to elect the representative of their choice), and it has long been argued that due to lower turnout among minorities that having a majority-minority district is not enough.
If MI loses a seat in 2010, its congressional districts will have around 736,000 persons. It will be impossible to draw two 60%-black CDs entirely within Wayne County. If the GOP combines the heaviest Democrat parts of the Detroit area to draw two urban-suburban CDs that are 55% black and a third urban-suburban CD that is, say, 35% black, I seriously doubt that the DOJ or a court will strike down such a plan.
As for Walberg's 7th CD, I know that his 3rd-tier opponent got 46%. The district gave President Bush 51% in 2000 and 54% in 2004, so it's not exactly Ottawa County there, and there was some lingering animosity from Schwarz and his RINO backers for having been defeated in the primary, not to mention the fact that DeVos's candidacy tanked at the end. Of course, it was also a terrible election for the GOP just about nationwide, and socially conservative, economically populist areas such as the ones in the MI-07 were exactly the places where many who voted for Bush in 2000 and 2004 turned their backs on the GOP in 2006 (see also the PA-04, KS-02, PA-10, NC-11, IN-02, IN-08, IN-09, IA-01, MN-01, OH-18, etc.). The Democrats have got to be kicking themselves for not running a good candidate in the district (there were several Dem state senators and state reps, some of them social conservatives, who probably would have won under the circumstances), but 2008 will be a lot tougher election for the Democrats to win that seat, since turnout should favor conservatives in that district in a presidential year (unless a RINO like Rudy gets the GOP nomination, in which case we may see low turnout among conservatives.
Oh, I forgot to mention your comment re: Monroe County. The MI-07 gave President Bush 51% in 2000 and 54% in 2004. If the MI-07 is redrawn in 2010 to exclude Calhoun County (give it to Upton, from whom I would take Kalamazoo away and give it to Ehlers) and the city of Jackson (give it to Rogers, who would have Lansing and East Lansing carved out), and to include all of Monroe County plus Gibraltar, Huron, Grosse Ile, Trenton, and maybe a couple of additional marginal townships in southern Wayne County, it would have given President Bush around 52% in 2000 and 55%+ in 2004. I think Tim Walberg would be very tough to beat in such a district.