Did nobody just backup those tapes the moment CDs became widely available?
Recordable CDs didn't appear for nearly a decade after the CD was introduced, and when they did they were insanely expensive. What they usually did was record to a newer tape, or some newer format like DAT, DASH or ProDIGI. None of these strategies would really pan out properly, however.
A new analogue copy would work, but we now know that between 1975 and 1995 Ampex tapes still had the sticky shed problem, which is exactly what we're trying to solve. With DAT the machines are intricate and fragile, being essentially tiny video recorders and AFAIK they haven't been made for some time. They're harder to keep working than say, a Studer A80 or MCI which mostly use off-the-shelf electronics and still have quite a large supply of parts and decent OEM support.
DAT also recorded at 48KHz instead of 44.1 so an eventual transfer to CD would be lossy owing to sample rate conversion, or plays back at the wrong speed, but there were quite a few DAT machines made so you could still do the transfer. Assuming the thin, fragile videotape in the DAT cartridge hasn't deteriorated.
DASH... machines sometimes turn up on ebay but are probably just scrapped because no-one wants them. Being digital they won't have 'the tape sound' so even the retro nuts like me won't touch them. ProDigi machines are like hen's teeth.
So no, a 1980s format conversion could potentially have made things even worse. Indeed, one of the favourite formats for budget digital recording was... Betamax.