I am aware that there are several changes between Windows 8.1 to Windows 10 with regards to mobile development.
Before I upgrade to Windows 10, I'd like to make sure that I can still develop Windows Phone 8.1 from a Windows 10 PC with VS2013 (Update 5).
Can anyone advise if I will have problems developing 8.1 phone apps with Windows 10?
TIA
You can still develop Windows Phone 8.1 apps (both Runtime or Silverlight) on Windows 10 with either Visual Studio 2013 or Visual Studio 2015 (I'd recommend upgrading to the latter).
Here's a quick snip of Windows Phone 8.1 projects in VS2015 on Windows 10: