IMO the only 'aliens' we'll ever meet will be humans who had left Earth for distant planets sometime in the future and whom Earth inhabitants have forgotten or fail to recognize for some reason(environmental adaptation causing inhuman features). A chance encounter in space will then be the 'meeting with the aliens' that many fantasize about.

As far as meeting intelligent species completely alien to our planet and our ecosystem, like the ones shown in Hollywood movies, I don't believe that's gonna to happen. Not now. Not ever.

The logic usually is that since space is vast, there's gotta be a planet somewhere that has similar environment like Earth and thus similar life forms inhabiting it. That's sound logic. My problem with that logic is... out of the 100 million+ species of life that are estimated to exist today and the countless ones that used to thrive over the last 4.5 billion years since the birth of our planet, only one... just one out of all those billions of species that existed over billions of years has developed far enough to type these words.

That's why when people say 'hey there are billions of galaxies out there, so we can't be the only ones' I ask them then that by the same logic, out of the billions of species that have existed on this planet there's gotta be more species like us doing the same things that we do? But there isn't. We are the only ones capable of doing things we keep hoping the aliens would do.

That's why I believe we are the only ones, on our planet as well as outside of it.