Long story short, InfoPath 2013 will work in SharePoint Server 2016, and will make migrations easier.
However, Microsoft appears to have kicked the can further down the road, leaving solution architects with more time to either wait for Microsoft to possibly reverse its decision to totally outsource forms development, or align with one of the MS-sanctioned forms + workflow providers and not look back.

See Vlad Catrinescu’s “Absolute SharePoint Blog”