Just heard someone on a YouTube video tell viewers to "stay tuned" for something coming up later, and I'm struck by how some phrases outlive their initial context. Literally, it makes no sense to say "stay tuned" on YouTube, but everyone still knows what it means and thinks nothing of it, even people who have probably never actually watched a TV channel via terrestrial transmission.
@scalzi
I'm your age and I don't think I've ever tuned a TV channel in the sense of fiddling with a continuous dial to find a station; I only recall channel selectors. So perhaps the phrase is from radio and therefore is doubly archaic?

@williampietri @scalzi I'm younger than John and had a TV with a tuner in my room as a kid, my parents old black and white TV

my grandparents also had tunable TVs —possibly they lasted better in the UK/PAL areas because we had fewer channels/a smaller spectrum? we didn't get a fourth channel until the late 80s