I agree with all the sentiments expressed here, but as someone on the inside, let me tell you that NO ONE at IMO gives a stuff about the heritage value of 500.
Do not forget that IMO were the bastards who merrily presided over the demise of our profession. The much touted GMDSS is a mess. Principally because ships do not carry dedicated communicators.
Alas, 500 would have never been made a heritage freq, despite all the good work of ex-R/O's.
Sad, but true.
So, at least 500 remains as a safety freq for the maritime service.