We've no plans to support other social platform extensions such as Jomsocial, ever. Sorry, but CBSubs and any of our other future developments are designed with CB in mind only (we use our own set of API).
You can display the subscription tab using an iframe if your like or a new plugin for Jomsocial to perform an ajax call to the following page.
index.php?option=com_comprofiler&task=pluginclass&plugin=cbpaidsubscriptions&do=displayplans
Additional you could develop a plugin for Jomsocial to render the Subscription tab inside of Jomsocial, which is also very doable.