Amazon has really good diversification, and they aren’t going away anytime. Look at IBM, they still exist after decades of being essential irrelevant.
It takes an awful lot to actually kill a company (often fraud or similar), but a company that is no longer dominant the same way is usually considered to have "died". Myspace still exists, but Facebook is clearly the one to beat in that sector.
If Amazon retreats to being AWS-only, I'll consider them to have "failed", even if AWS continues to be a success.
AWS is probably the biggest moat they have, but not often what people think of by "Amazon".