Legend saturation has been 500 and may have risen now.
Tour Legend saturation was 500, too, and may be 600 (to 700) now to become a Champion.
"Saturated" TLs had to play 200 more for C tier, and their average has been jacked up once.
Talking of ranked storkeplay, and Par3s and Par5s do not count in.
There are no official numbers except those 200, so we have to wait for news from players counting, experiencing and posting it.
IMHO, it's hardly something we should be waiting for - it just happens. You'll see it when out of the blue the average starts to drop severely and even on scores higher than the average itself - non-linear maths.