Thanks for your questions, @iamnarendrasingh!
Briefcase is an important tool in many users' workflows. It lets people take complete control of their data by doing local backups, by automating tasks through the command-line interface and by pulling directly from clients like Collect. Right now development on it is stalled because the code is brittle and there are several issues related to each other that need fixing (e.g. logging). I think there's the opportunity to help many users by making improvements to Briefcase such as Adding bulk export of data to Briefcase GUI.
ODK includes a set of tools like Aggregate, Briefcase, Collect etc but it also defines standards such as the ODK XForms and ways for the tools to communicate between each other. Many tools such as Enketo or Ona are compatible with ODK without being core tools. They are important parts of the ODK ecosystem.
In this context, I said "Ecosystem-wide" because ideally clients and servers across the ODK ecosystem would allow the same kinds of changes to forms and communicate them in similar ways. Right now some use the version field in forms and some don't and even those that do don't use it consistently! So this is an area where I think the TSC could outline some very useful new standards and guidelines.