Planned obsolescence - Wikipedia
Releasing a new model doesn't automatically make an older one non-functional.
It doesn't even make it obsolete, provided that the whole sector (and by this I mean from content production to fruition through processing).
1080p
video is on the verge of being obsolete, because we now have 4K cameras, 4K software, maybe some channels (?), Tvs, etc.
I'd say that one of the main obsolescence threshold for pictures is about 8 MP, give or take some cropping leeway.
After all, very few people print, even fewer print big, and 8 MP take full advantage of a, say, 50" 4K TV.
I mean... the "Market" can well say: "Your old camera is OBSOLETE! it's the wrong color", but it's up to (intelligent) people not to believe it...