I like the idea of Generation 3, but there would have to be some official designation from Hasbro for me to call it that.
Personally, I don't see any need to call those toys anything as a whole. I'd call the ones that were Classics "Classics", the one that were Universe "Universe", etc. They're different lines, just because individual fans might put the toys together on the same shelf, it doesn't make Generations toys the same line as the Classics ones.