no, not dead, you could still run it. but it had a serious bug in it all along that made discovery of other AmericanCoin servers fail via IRC; so after AMCCoin lost their domain, and DNS seeds were no longer useful for finding servers, very few connections were found. some of the last I had, at least a year ago maybe more, were 128-73-148-39.broadband.corbina.ru and ns3311733.ip-5-135-163.eu. remember those? anyway I never thought to troubleshoot the problem until you mentioned the other day that you couldn't sync. that's when I got motivated to locate and fix the bug.

so, in short: you can run the old client as long as enough other people are running the fixed one.