Mendix mainly depends on JVM. So technically it won’t be a problem. However, I can think of the following risks:
Considering the above, I would say, clone your machine (hopefully it’s a VM) to create a test environment. Upgrade that machine to windows 2016 and test thoroughly.
I’d advise build a fresh environment and upgrade your mendix version. Mendix 3.x has been out of support for many years. Your app is probably at high risk (internal apps are still hackable). Some critical vulnerabilities have been fixed recently.