This thread might be of interest to you:
https://bitcointalksearch.org/topic/necronomicon-thread-altcoins-which-are-dead-588413The Tenebrix network is weak, but still functioning. I've sent and received TBX as recently as this year.
I usually sync the blockchain with my wallet every 6 months or so, usually during computer spring cleaning time, during which I delete all the junk crypto files that accumulate. I could never bring myself to delete my TBX files, however. Altcoins come and go and are nearly all rubbish, but the original alts like TBX seem worth saving for the lulz, the nostalgia, or the history.
The Fairbrix network is a bit stronger, I've noticed, but not by much. Of the old altcoins, Liquidcoin has the most spotty network and is the only one I can't consistently sync. I was able to mine LQC until the end of last year, but the network has become extremely weak since then.
I see no reason why Tenebrix code couldn't be updated. IXCoin and I0Coin have been updated, indirectly because they have benefited from being merge mined all these years, which not only secured their networks but also kept the coins in the crypto-consciousness; whereas the non-MM coins like TBX and FBX have been relegated to mostly leftover PCs and slow CPUs. Yet it wasn't long ago that IXCoin and I0Coin seemed just as ancient as TBX.
I guess you could say that a coin is dead when there are no longer any people maintaining the network. But even such a coin could one day be revived. The code is open source, after all.
