It' looks like Microsft changed it's strategy when it comes to the support of InfoPath in SharePoint 2016 on prem.
According to latest Microsoft news, good old InfoPath 2013 is still supported in the new SharePoint version. For now it ll be the last release of InfoPath and it could help to migrate the masses of enterprise customers, which are still on SharePoint 2010. Maybe we ll see a direct upgrade path for such customers and InfoPath is one cruzial point, when it comes to migration of workfows or customized list forms,
See detailed Information here: http://blogs.office.com/2014/01/31/update-on-infopath-and-sharepoint-forms/
There are good 3rd Party products on the market, but in my opinion lists and related activities are one of the core functions in SharePoint and therefore should be massively optimized by Microsoft itself. Also I don't really see Word and structured documents as a nice way to optimize this use case.
At the same time, efforts in FoSL (Forms on SharePoint List) were stopped and there is no clear Roadmap right now. Maybe we ll see smth totally new...