Whatever the merits of finding in favor of cross-district busing in
Miilliken, it will be a political disaster for the Democrats. To give you an example of the political effect of
Milliken in the Detroit suburbs:
In 1972, when the busing order was pending, some Detroit-area districts came very close to defeating Democratic Representatives who had previously won easily. In MI-12, James G. O'Hara who had won 76.1 to 22.9 in 1970
https://en.wikipedia.org/wiki/1970_United_States_House_of_Representatives_elections#Michigan only narrowly survived with 50.8 percent to 49.2 percent in 1972.
https://en.wikipedia.org/wiki/1972_United_States_House_of_Representatives_elections#Michigan In 1974, with
Milliken decided and the voters of Macomb County assured that their children would not be bused to Detroit schools (and Detroit children would not be bused to their schools) O'Hara went back to winning with 72.2 percent!
https://en.wikipedia.org/wiki/1974_United_States_House_of_Representatives_elections#Michigan O'Hara had disappointed his old liberal friends by coming out strongly against busing, but even that was almost not enough to save him in 1972.
In 1970 in MI-14 Lucien Nedzi won 70.0 to 30.0. In 1972 his district was extended further into the suburbs but they were largely Democratic UAW-organized blue collar suburbs and it was thought that he would still be safe. He won, but only by 54.9-45.1
https://en.wikipedia.org/wiki/1972_United_States_House_of_Representatives_elections#Michigan In 1974, with the busing issue gone, he got 71.2 percent of the vote.
https://en.wikipedia.org/wiki/1974_United_States_House_of_Representatives_elections#Michigan
In 1972, Democrats expected to win the newly created suburban MI-18, consisting of Democratic-leaning suburbs in southwest Macomb and southeast Oakland Counties. Instead, right-wing Republican Robert J. Huber won it 52.6 to 47.4
https://en.wikipedia.org/wiki/1972_United_States_House_of_Representatives_elections#Michigan In 1974, with the busing issue gone, Huber was defeated by Democrat James Blanchard 59.0-40.4--an unusually large margin of defeat for an incumbent.
There is no reason to expect the busing issue to play out politically any differently in other suburbs throughout the nation.