However, it appears that at this point in time, signature files are the primary (and unfortunately) looking backward solution. They work, against know malware, but they're a dinosaur, sledgehammer type solution.

Heuristics are a growing part of the solution. Perhaps stopping malware in the clouds will be part of the ultimate solution. Signature files will not disappear in the next couple of yearsHeuristics will probably supplant them in conjunction with stopping malware in the cloud. You need more than one technique.