UPDATE on the Constitutionality of Michigan's Sex Offender Registry Act as of December, 2017.
The Michigan Supreme court heard the 2nd set of oral arguments in People v Boban Temelkoski on October 11, 2017. As of this update, the court has not tendered its decision.
You can read all about the parties and their positions here: http://courts.mi.gov/Courts/MichiganSupremeCourt/oral-arguments/2017-2018/Pages/150643.aspx
Perhaps the biggest unknown, and the most significant impact, may be on the current Tier 3 offenders, who where put on the registry, under a "listed offense" prior to the 2011 amendment. Prior to that amendment, they were required to register for 25yrs. After the amendment, all old and new offenders were put into tiers, and Tier 3s were required to register for life. If the Michigan Supreme Court determines that part of the amendment as unconstitutional, it may revert those Tier 3 offenders, who were already registered prior to the 2011 amendment, back to their old registration requirements (25 years vs. Life registration).