I share your view that broadcasting radio waves is a time-limited phase in human development; the airwaves are limited. But I don't agree with you that it could

I share your view that broadcasting radio waves is a time-limited phase in human development; the airwaves are limited. But I don't agree with you that it could last "a few thousand years"; radio broadcasting depends critically on an electronics industry that only works at scale. Those industries depend on a stable, modern civilization, and I see no reason to think that modern civilization should last longer than earlier civilizations. I completely agree that the duration during which a civililization can be expected to broadcast radio is extremely short, in galactic terms. So I think the likelihood is that if you do detect a radio transmission from outside the Solar System, by the time you receive it, the sender is dead; all his descendants have died; his planet's climate has changed, so that his species has been compelled to evolve (or die out); and his electronics-supporting civilization is long gone. So I don't carry much water for SETI.