In general, browsers shouldn't even revalidate the file as long as it's younger than the max-age lifespan.
They may choose to "evict" it from the cache, but that's generally based on a policy of recent usage and needing to free up/prioritise disk space for more recent assets.
I'm now interested to see how different browsers handle refresh/force-refresh - whether they revalidate a file that's still considered fresh, and whether they set request-headers to bypass upstream caches too. Maybe an experiment for the xmas holidays :-)
