I would not say so. Just getting worst and less used. But, it is very far from extinction.

Digg is 'still around', too.

Perhaps, but it needs a proper competitor before it truly fades to irrelevancy.

Maybe it doesn't need a competitor but something that supersedes its design while staying inside the community of communities structure. Most Reddit clones do nothing better than Reddit, they just attempt to painstakingly emulate it. Karma is gamed too easily. Why hasn't someone tried to rank content by a mix of votes and quality indicators (grammar checks, NLP sentiment, engagement)? Innovation usually disrupts.