Oracle does not generally announce release dates in advance.
I'm not sure what 'work' you are hoping to save since sql developer doesn't really use an 'install. If those users don't need a tool then why install one to begin with? And if they do need one then install the latest current version.
as rp0428 said: you won't get a release date. On the other hand there is a new db version and the current SQL Developer does not support every new feature. So you can assume/hope that the new release will be not too far away.
But is installing a new version really so much work that it justifies to wait an indefinite time for features you might not need, compared to the fact that you cannot use the tool on the other machines?
When we do post an update, it will be an Early Adopter (Beta) release. That EA will be updated several times as we identify bugs and tweak new features based on user feedback provided here. At the conclusion of the EA program, we'll officially release the next version. Said version will be fully supported by My Oracle Support.
As the other posters have said, you're not saving yourself that much work by waiting, a simple unzip of the archive and your install/upgrade is done.
I do recommend leaving the previous version on your machine for a few days/weeks after an 'upgrade' in case the user finds any issues and they want to 'go back.'