I've spent the last couple weeks logging stick time with Atmel Studio 6 and I'm convinced the 'market' for VM/DT is there. As supporting evidence, there are at least two 'customizations' which support Arduino development in Studio 6. One is a three part 'tutorial' by Jaycon Systems located here:
http://www.jayconsystems.com/tutorial/atmerpt1/ http://www.jayconsystems.com/tutorial/atmerpt2/ http://www.jayconsystems.com/tutorial/atmel/ The other is by Omar Francisco, here:
http://omarfrancisco.com/arduino-programing-using-atmel-studio-6-0/ The Jaycon approach integrates the Ardo toolchain into Studio 6. It's a checklist of labor intensive manual steps and is more a Proof of Concept than a turnkey installable. The Francisco approach involves a downloadable zip which gets manually wired into Studio. Both integrations have to be tweaked each time you change device type (UNO vs Nano, etc.) or COM port.
While I commend both authors for their efforts, I doubt that either approach will gather adherents in large numbers. There is simply too much manual intervention required for context switching between projects. And manual configuration means lots and lots and lots of support issues. Businesses which attempt to sell technology to 'civilians' most often fail because they become overwhelmed by support calls.
The good news is that the shower of user comments on the Francisco page indicates market pressure for something 'better than' the Arduino IDE. The Ardo IDE is a superb introduction to MCU development but making it approachable by newbies necessitates keeping it rather simple.
Banzi & Co. did a wonderful job of convincing artists and photographers that they can leverage modern technology without having to learn anything about "Computer Programming". After gaining experience, however, there are likely to be developers who begin looking for more advanced development features - global search and replace; code management hooks; etc. - but who, for whatever reason, are reluctant to try Visual Studio. This is the target market for VM.
From this it follows that VM needs to be as completely integrated with Studio 6 as it is with VS. Users should be able to switch COM ports with a menu click-down, particularly one that shows which COM ports are currently connected. They should similarly be able to select/change their device type with a drop down. The Ardo libraries and user Sketchbook should be fully and seamlessly integrated.
Most of all, VM should be a single, turnkey install that requires no manual configuration. We're not after the AVR Fanboys who use EMACS to balance their checkbooks. We want the schoolteachers and graphic artists who are outgrowing sketches. Download the VM installable, run it, and you're in business.
In short, the Visual Studio integration should serve as the design point for Studio 6.