Is Mankind Doomed? if so how do you think it will end?

nukes, 100%, were not even going to make it to global warming

Even if we could somehow manage not to kill ourselves off as a species in another 4 billion years, the sun will eventually die and with it, us here on this planet. Hopefully, we'd be traveling to other stars by then, but that's a big if and hard to imagine where we're at now. There's no way to know one way or another for sure, but my votes on survival finding a way somehow.