I've been asked to take a look at some of our current plugins and alter them for our upgrade to 2015. However, looking at the SDK it says the system requirements (see here) are Windows Server 2012 (and 8, but not relevant for me) and Visual Studio 2012 or 2013.
I'm currently on Windows Server 2008 R2 and using Visual Studio 2010. So can I still develop the plugins for 2015 or do I need to upgrade? Surely from my point of view it's just referencing a new dll?
UPDATE
Thanks to Guido for the answer, which is true. However, for anyone reading this I would recommend checking what the latest version of the CRM SDK Developer Kit is. At the time of writing this the latest version is the CRM 2013 version and is compatible with VS 2012 only, though a hack (found here) can be used to try and get CRM 2013 Developer Kit to work in VS 2013. I've opted for the route of installing VS 2012 instead.
You need at least Visual Studio 2012 to write plugins compatible with CRM 2015.
If you use CRM 2015 SDK dlls, the target of your project should be .NET 4.5.2