It supposedly happened at the same time the gun boards went away. From memory it was 2018 when it was to be active, that is all I remember.
If I don't see anything by the end of the year I will have to go to the clerks office. It would be nice to just do it online, but as you said I doubt anybody is in a hurry to something that has no penalty if they don't do it.
A quick search found an Mlive article https://www.mlive.com/news/flint/index.ssf/2015/12/legislation_does_away_with_gun.html (https://www.mlive.com/news/flint/index.ssf/2015/12/legislation_does_away_with_gun.html)
ETA:
So this says Dec 1 2018
http://www.legislature.mi.gov/documents/2015-2016/publicact/pdf/2015-PA-0003.pdf
Page 16 - Sec 51 (2) Subject to subsections (8) and (9), an application to renew a license to carry a concealed pistol may be submitted not more than 6 months before the expiration of the current license. No later than December 1, 2018, the department of state police shall provide a system for an applicant to submit his or her application to renew a license to carry a concealed pistol online or by first-class mail and shall accept those applications on behalf of the county clerk as required under this act at no additional charge.
http://www.legislature.mi.gov/(S(cbcebafdyqug1kqdsbjimjxj))/mileg.aspx?page=GetObject&objectname=2015-SB-0034