As I recently covered, Microsoft has announced that the Visual Studio Premium with MSDN and Visual Studio Ultimate with MSDN editions will be combined into a single, new edition for Visual Studio 2015 – Visual Studio 2015 Enterprise with MSDN.
If you have an active Visual Studio 2013 Premium w/MSDN subscription, you will be upgraded, for FREE, to the Visual Studio 2015 Enterprise w/MSDN edition when the final product becomes available later this year. Once your subscription runs out, however, you will have to start paying for the new Enterprise edition (because the Premium edition will no longer exist).
Although the price for the Enterprise edition will vary (based on whether or not you are buying a single subscription or if your company has a volume licensing agreement, etc.) one thing is certain – the price will likely go up from what you are currently paying for your Premium subscription. If you are curious about the features that you will be gaining as you (eventually pay to) move from Premium to Enterprise, I have listed them below (based on the information that is available today).
The following features currently exist in the Visual Studio 2013 Ultimate w/MSDN edition but not in the Visual Studio 2013 Premium w/MSDN edition. These features will become available to you as you are automatically upgraded to Visual Studio 2015 Enterprise w/MSDN edition later this summer:
- Debugging and Diagnostics
- IntelliTrace in Production
- IntelliTrace (Historical Debugging)
- IntelliTrace Performance Indicators
- .NET Memory Dump Analysis
- Code Map Debugger Integration
- Testing Tools
- Web Load & Performance Testing
- Integrated Development Environment
- CodeLens
- Architecture and Modeling
- Architectural Layer Diagrams
- Visual Studio Online Services
- MSDN Subscription: Software for Development and Testing
- Microsoft Azure – Increases from $100-USD credit per month to $150-USD credit per month
- Other MSDN Subscription benefits
- Pluralsight Training – Increases from 20 courses for 12 months to 30 courses for 12 months
If you would like to see the full list of features for Visual Studio 2013, click here. Likewise, to see the full list of features for Visual Studio 2015, click here.
Gaining IntelliTrace and CodeLens alone is a great win but getting the extra Azure credit (an extra $50-USD) and Pluralsight training courses is icing on the cake! 
Today, roughly 88% of the developers in my organization have a Visual Studio 2013 Premium w/MSDN subscription with the remaining having Visual Studio 2013 Ultimate w/MSDN. After Visual Studio 2015 is officially released later this summer, we’ll be able to move 100% of our developers to the new Visual Studio 2015 Enterprise w/MSDN edition where everyone will be able to take advantage of these features! Great news!