This seems quite plausible to me. The Drake equation should probably include another variable, how sensitive to alien intelligence this species is. Given that we routinely fail to notice sentience within our own species, it’s not hard to imagine that something like “so long and thanks for all the fish” could be going on under our noses, and we’d be oblivious.
There are two sub-groups of possibility here, Alien intelligence could be actively hiding itself, waiting until humanity grows the fuck up, or we’re simply not correctly interpreting the abundant signs of alien intelligence that are all around us. They’re not mutually exclusive, there could be plenty of clues as well as some kind of masquerade. I might call these the “Easter egg hunt hypothesis”.
