but I think it's highly likely we will find signs of life on ecplanets by looking at them, perhaps even of intelligent life.

If our own civilization is anything to go by, intelligent life ramps up very quickly from an agrarian base to sending powerful radio signals, then quickly quiets back down as it builds out wired infrastructure and local wireless.

We've probably got better luck detecting atmospheric gasses indicative of industrial processes though.

Computers will become as smart as humans, but only for a very brief moment. After that they will quickly surpass us and become the dominant "species" on earth.

I'm not convinced of this. People just seem to assume that a strong AI will be able to crack the intelligence engineering problem automatically, which seems overly optimistic regarding the difficulty of the problem. Engineering a super-intelligence probably can't be achieved through iterative improvement because there's certainly going to be diminishing returns that come from simply throwing more hardware at the problem.

There are probably fundamental limits to the capabilities of neural networks. Going radically beyond human intelligence will probably require a different approach, and an AI would be in no better position to explore those alternatives than humans are. Why does everyone just assume that a strong AI will automatically be able to solve it? If we lack the basic science and engineering to propose a route to a radically superior intelligence, then the AI won't be in any better position.

Though if you're talking dominant species in terms of numbers, maybe. If we can figure out how to mass produce generally intelligent AIs, then absolutely they'll win a numbers game.

For the first time since Homo Sapiens walked on this earth, we're not in charge.

We've never really been in charge. In terms of macroscopic organisms, this is pretty much the planet of the plants and insects.