My take is that the democrat base is fired up. And, the GOP didn't mobilize...either because of apathy or just pissed at the way the US is being run. It is very much a referendum on Trump, and the first warning sign to his administration that the gravy train of his bullshit being rubber stamped by an ineffective congress will end in 12 months.
But Trump knows this already. Why else would he ask Texas to redistrict the state for the 2026 mid-term elections to give him (hopefully) more seats? Because he knows he cannot win on his record. I am well aware that things can change dramatically within the next year. But Trump will likely have triggered a recession by then. And he continues to do things that are unpopular for the average person not in the cult. And it appears that the cult's numbers are shrinking.
I don't know if Newsome will become the challenger in 2028, but he is good. He is smart, a great communicator and someone who I think can play the game in a way Trump hasn't faced before. But, a lot can happen between now and election day.
Now, as for Mamdani, I think he is tapping into a populous that is sick of seeing the rich become richer by basically standing on the necks of everybody else. They see rent prices rising, which doesn't really hurt the mega rich. And, for anyone saying the wealthy will leave...please. NYC is the place to be. It has the nightlife, the restaurants, the cultural stuff, sports and theatre. It is the financial hub, where deals are made and fortunes are won or lost. Where else would they go? Texas? Florida? lol. Maybe for the winter...