New rumors suggest, that the successor to the Surface Pro 4 might come with Thunderbolt 3 port, more storage, Kaby Lake processors and possibly an integrated fingerprint sensor. It might be released as early as Spring 2017.
http://www.notebookcheck.net/Microsoft-Surface-Pro-5-rumors-Thunderbolt-3-Kaby-Lake-and-more.186750.0.html