Yeah that MI poll caused a bit of a stir but more data needed I think. One or two polls aren't a trend. Besides which, there aren't enough 'traditional' GOP voters in MI to do what you say, it's just not a red state despite the tiny margin DT won it by four years ago.
Dems should pick up senators in AZ, CO & ME with NC & IA both looking pretty good for them too. They have a chance of gaining one in MT, one or even both GA seats and even KS and SC.
Balance that with the probable loss of AL and even if we throw MI into the mix as one the GOP could gain, it's still a 10-2 lead in terms of chances to gain seats in what looks like being a wave election. I'd say the Senate looks like going blue on balance, though a clean sweep of targets/defences would be a surprise
ETA: the Dems also have the advantage of defending far fewer seats than the GOP in this cycle and a high proportion of those just aren't under threat - NM, OR, IL, MN, various north eastern states etc just aren't going to be lost