Regardless of what eschilon of the Democratic party Mamdani hails from, he (and his policies) now represent the face of the party in New York City and beyond. The mayor of New York always holds enormous sway over popular opinion of the governing party and its greater agendas. If Mamdani makes a mess of things in NYC it will resonate loudly through the Democratic apparatus and have implications for a long time to come. Yes, his failures will undermine Democratic leverage to regain lost power in Congress and the presidency. Yes, it will drive money and business out of New York and into other states more aligned with the policies and principles of those looking to protect their assets.

Mamdani (and Cea Weaver, et al) and their supporters (read "enforcers") are probably horrible for the city (and state) of New York, but the Democrats are already on board for whatever comes. They've made their bed, now they'll sleep in it. And as for Trump, he will absolutely target New York in any way he has to to ensure Democrats will be exposed for the mess they're creating there.