EDIT: related story on SF's private lines http://stamen.com/zero1/
If it succeeds, it does mean it succeeded in the conditions of Detroit, as mass-transit is something so delicate it inherently must be optimized for the city in which it operates. That said, I do absolutely wish them luck living in a city with what I consider absolutely horrible public transit[1]
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[1] This is subjective, highly of course. And given the population boom taking place in Austin, Texas it's somewhat hard to fault CapMetro entirely for the woes of riding the bus. I will say though many will find themselves in agreement living here seeing CapMetro time and time again implement projects that utterly fail because they made no sense to begin with. Yep, I'm looking right at you Red line.
Manhattan's mass transit system is largely intact from its peak (except for the incomplete Second Avenue Subway, to replace the demolished Second Avenue Elevated the East Side), and has become better integrated from the private era when there were three competing systems. The trolley lines were more significant in the outer boroughs, and could reach speeds & frequencies similar to their best years with proper implementation of modern light rail or bus rapid transit. That would require the political will to take away surface right-of-way from the (boisterous, wealthier) car-driving minority.