IMHO the real source of a lot of these problems is that the subway system is a city resource that is primarily payed for by city taxes (and fares of course) but it's actually administered by the state government (which the MTA reports into). If it was a city controlled thing it would be a huge huge issue in every single mayoral election. But it gets somewhat drowned out in governor elections.
The city retaking control of subway raises the question of who will pay for the operation and capital costs. The MTA derives allot of its funding from tolls through the Triborough Bridge and Tunnel Authority which generated $1.8 Billion in 2016. It's unlikely the state will give TBTA back as well.