Even when Alan Pardew (and I take great pleasure in being the first to mention his name in this forum) called opposing soccer manager Manuel Pellegrini "a fucking old cunt" it wasn't perceived as a slur on his elderlyness. It was the cunt bit that got him in trouble - and, even then, not that much.
I feel like it's becoming a word describing people that have passed their prime (~35+ yo).
Yes, I'm fully aware that the word initially described people that were born during the baby boomer years (~1950) and that the people that are currently 35yo are millennials.
80 years ago was 1944 - not exactly a boom year. Most are 60-65-70 and would not consider themselves elderly. It's a very loaded word.
You go directly from middle aged to elderly, there isn't a step in between. Being elderly can cover a very wide range of years.
That said, I've had friends that were elderly in their mid thirties.. State of mind and all that.
(Rationale being retirement planning advisors encourage people to make the most of those first ten years (65 to 75) to do bucket-list things while (usually) they still can)