Perhaps for state legislature maps where there is a greater number of seats there could've been a way to draw them in Michigan fairly that actually gave Democrats a lead. Although I would still think drawing districts compactly would give the Republicans an inherent advantage because of the concentration of Democratic votes in cities. But for U.S. House seats it IS impossible to draw the districts where Democrats actually have more seats without ridiculously gerrymandering them by tendrilling several of them into Detroit.
There's certainly the possibility they win the Senate next year, although I wouldn't say probably at this point unless the GOP nominates someone like Trump, which I believe they will not. They certainly have the advantage in Wisconsin and Illinois, but they still have to win 2-3 of Florida, Ohio, Pennsylvania, and New Hampshire depending on who wins the Presidency. They also have to hold Nevada against Joe Heck, a good candidate who's been strong in a 50-50 House district the last few cycles. But it's certainly possible.
That will probably only last 2 years though as Democrats start out as underdogs in Indiana and Missouri and 50-50 at best in West Virginia, North Dakota, and Montana. And Democrats have an inherent disadvantage in the Senate as Republican states have shown no problem throwing out otherwise entrenched Democratic candidates for Federal seats like Mark Pryor, Mary Landrieu, and Blanche Lincoln and other strong incumbents like Kay Hagan and Mark Begich. On the other hand Maine has shown no qualms about repeatedly electing Susan Collins and other slightly democratic states like Wisconsin, Pennsylvania, and Iowa have elected several Republican Senators.