As with most operating systems over the years; Microsoft has decided to stop supporting Windows 7 and Server 2008 R2 after Jan 14, 2020.
-No Technical Support from Microsoft
-No Additional Software Updates
-No Additional Security Updates
Going forward, if you continue to use Windows 7 and Server 2008 R2, you may experience times when software is no longer able to work, or not able to update, etc.
For users with Office 365 subscriptions, this may mean users may not be able to access excel or word documents, access e-mail, etc
Unfortunately, how critical this issue is, is mostly determined by the changing needs of the services you connect to. As the internet or third-party software continues to evolve and security demands increase; Windows 7 and Server 2008 R2 could be left out of necessary updates in order to continue connecting or hosting those services.
You could do the proactive method and upgrade before you starting experiencing issues, or you could wait until you start experiencing issues on the computer. For businesses that wait, this could mean your employees (or even yourself) could find themselves unable to work on a specific task (not recommended).