Migration Windows

Given the fast approaching Windows 2008 Server EOL, we would like to migrate to higher versions of windows server (2012,2016...). We have around 4 of 5 machines in house to migrate with a TFS server, IIS, and some other software. More importantly one of them is the AC/DC. We would like to either migrate that one into the cloud (Office 365) if possible given all the software which access it today (mostly TFS and Release Management), or if that's not possible make a redundant AC/DC to be able to load balance between both servers.