I just got off the phone with the powers that be and all non-ORV trails from Toivola north to Copper Harbor are closed to snowmobiling. This is due to easements and insurance ending midnight on the 31st. The Bill Nichols trail (Mass City to South Range) is an ORV and would thus be legal to ride on.
Not sure how the folks south of Toivola are working things with easements and insurance, but can say that any trail north of the bridge to Copper Harbor that is not a designated ORV trail would not be legal to snowmobile on. I am not sure if or which trails north of the bridge are designated ORV, but please check folks.
Of course there is the chance that the powers that be that I talked to somehow did not get a message that there was this one final week, but I am out of town and cannot call the DNR to confirm exactly what the scoop is.
-John