If MI Legalize passes and the new medical marijuana rules in 4209 pass, the there will be two parallel systems of licensure and enforcement. The bills don't prevent MI Legalize.
What will caregivers face in such an environment? Well, there would be one MMMA system that they would not be able to sell their overages into. Then, there would be a separate system with local licenses available per the terms set by local governments. Those terms could allow caregivers to supply the adult-use market. Given that there will be overages, it would be smart for communities to allow caregivers to move their product into the legal market. Otherwise, there'll be less revenue and less success in moving sales into the legal market.
Given the differences, there are obvious advantages for everybody in the market under MI Legalize, except of course the individuals who would score the licenses in a heavily regulated market.
Of course, it's not out of the question that some creative judges overturn the will of the people. That is a concern in any scenario, but it is more concerning when you're on the right side of public interest. The GOP does control the courts.
Also, let's not forget that there will be legal challenges no matter what. There will be likely be legal challenges to HB 4209 as an amendment to the MMMA. Without a 3/4ths vote, 4209 could go the same way as transport rules passed in Dec 2012.