I won't make a judgment on saying he won't win in spite of this, but I don't think this is effective in this context in an election which, based on Trump's own campaign, relies greatly on backfilling suburban women with Black and Latino men.
I also think the suburbs of all of these cities (Detroit, Philly and Milwaukee in particular) are changing a lot... They are growing, they are more diverse, and the people who live in them don't necessarily respond the dog whistles in quite the same way.
With respect to Detroit, it isn't L. Brooks Patterson's Oakland County anymore... People dont necessarily harbor the same animosities that they used to, and on a cultural level, especially seen during the Tigers and Lions playoffs runs, the "Detroit v Everyone" framing doesn't die off at Eight Mile. There's a level of cohesion today that wasn't the case 20 or 30 years ago