All fascinating stuff but I am not going to hold my breath. Any ET life will have to be in our own galaxy for any chance of positive ident. Also they will have to be older than us in technology as our technology is only poking out through about two hundred light years distance all round. So they are hiding from us or their technology has not reached us yet.
The only other option is discovering a planet in the goldilocks orbit with O2/N2 signature similar to us that might indicate a possibility of life. Only way to prove such a discovery is travel there. Even our best probes are going to take generations before we get a positive answer.
As for the possibility of EXTRAterestrial life, how would we know even if we find it?
BUT! That doesn't mean we shouldn't stop looking.