Might there be a real-life zombie apocalypse one day? Not likely, but then again, the way zombies have chomped their way into our pop culture the last several years, it’s maybe a bit less implausible than it once was.What IS increasingly quite plausible, alas, is a scary global pandemic, and “World War Z,” the long-awaited Brad Pitt thriller, cleverly melds that real-life threat into the more fanciful zombie premise. Talk about more bang for your buck: Once you’ve settled back into your seat after a good snarling zombie chase, there’s nothing like the thought of a SARS outbreak to get the blood racing again.But let’s just say right here that the one apocalypse you won’t see in “World War Z,” based on the 2006 novel by Max Brooks (son of Mel), is an artistic one.