Hi Nikhil,
You gather correctly: Right now wyBuild assumes your userbase should come up to the latest release.
We have planned the feature you're looking for to be built into the next release of wyBuild, but are still reviewing our roadmaps and timelines before we have the target release date.
In the interim, you could roll-your-own, implementing what you're looking for by following our guidance on limit-updates and passing the interim version to the server script, as outlined here:http://wyday.com/wybuild/help/limit-updates.php