Agreed. Assuming we avoid extinction, it's not obvious we'll be able to recognise ourselves a few hundred years from now, never mind a few thousand. And a gulf of a few million years would be utterly incomprehensible.
In fact I'd be very suspicious if recognisable alien life appeared and knocked on our door, because it would literally be so astronomically unlikely I'd be skeptical about taking it at face value.
Well, yes and no - plenty of terrestrial organisms that haven't shared a common ancestor with us for hundreds of millions of years can recognize us (like, say, crows). But I agree that easily recognizable sentient aliens visiting us in person is very unlikely, due to the scale of the universe.
In fact I'd be very suspicious if recognisable alien life appeared and knocked on our door, because it would literally be so astronomically unlikely I'd be skeptical about taking it at face value.