Plug-ins are not automatically migrated and you are going to need CC 2015 compatible versions, anyway, that are designed to work with the updated renderer.
thanks for the answer
So can I just drag and drop the plugins from cc2014 to CC 2015?
THat would be great, but probably there are going to be compability problems, wouldnt it?
Feel free to move your plug-ins around at your own leisure and at your own risk, but since most vendors already have CC 2015 enbaled versions avialable or at least announced, this seems slightly unnecessary...