Anything short of complete nuclear devastation that ends in the total annihilation of the human race is a bright future, and will continue to proceed towards that bright future at all times, though there may be very minor setbacks along the way.
We are so, so close to offworld colonization. We'll be living on the Moon this century, and on Mars next century. I firmly believe that. It's possible that someone may set foot on Mars in my lifetime--though I'm sure they would not get a return trip. Offworld colonization is the first step to immortality.
We are rapidly approaching something that resembles an artificial-intelligence singularity. Okay, maybe I don't believe in a real technological singularity. But at the very least, it'll be along the lines of a bunch of metaphorical mass gathering together and forming a star and planets, instead of drifting aimlessly in space as random unconglomerated matter. The things that will come out of this are incredible.
Even if we do manage to kill ourselves off, our ancient rusted relics are going to absolutely blow the minds of whatever sapients are next to evolve some millions of years from now. You can bet they'll learn from our mistakes (IE don't blow yourselves up dammit).
But more realistically and closer to the present: The world's infrastructure is increasing at a rapid pace. Disease is declining. Starvation is declining. There's barely such a thing as a third-world country anymore: Some places suck to live, by North American or Western European standards, but they're improving day by day. The belief that there is a firm distinction even between "first world", "second world" and "third world" is a myth. But, again, infrastructure is being improved, and technology that is directly relevant to poor regions is constantly advancing. It's not going backwards, it's just not.
Environmental science and awareness is improving faster than we're killing ourselves. Yes, we will suffer from global warming, but we are smart monkeys gosh darn it. We will adapt and we will slow and eventually stop the process, and maybe even take a couple shots at reversing it. No matter what happens, though, life will go on...WITH us. And even if we make a chunk of the equator uninhabitable, and only survive by decreasing insolation with artificial smog, you know what? We can deal with 80% of the sunlight we used to get, and we can learn to live in those deserts.
Oh yes. We are clever monkeys indeed. The future is always, always, unceasingly bright.