Since I am planning to buy a new MacBook Pro (2017) and currently working on a Windows 10-device on a ASP.NET MVC (Not ASP.NET Core MVC) project for my internship, I was wondering if it is possible to continue developing the same project in Visual Studio for Mac.
To put it in other words: Is it possible to develop ASP.NET MVC applications in Visual Studio for Mac?
I tried to Google this, but I could only find ASP.NET Core MVC projects being discussed for VS for Mac. The current project is NOT a Core project, but just an ASP.NET project.
I really don't want to install Windows either on my MacBook Pro or on an external drive.
As you've correctly surmised, it's not possible to build ASP.NET MVC projects on the Mac that aren't based on .NET Core or Mono. So if your project is currently targetting ASP.NET on .NET Framework 4.x, the you'll either have to stay on Windows:
Or you can convert your application over to Mono or .NET Core, depending on your dependencies that may be relatively easy, or very hard or anywhere in between.
You could also decide to use Visual Studio Team Services to build your code on a Windows Hosted agent and edit the sources on yoru mac, you'd have to forego the ability to compile or run your code locally.
You can also decide to "rent" a virtual machine in Azure (maybe your have MSDN credits you could use for this purpose?) and remote desktop to that machine to work on your project.