Eh. Couldn't be more off on your reasonings for "HD Twins". Though your least annoying inclusion and it can be used in negative ways, as a term I find it completely legitimate to describe the polarization of console hardware strength that exists this gen. It is an interesting situation, the two HD twins are so called because of their standing in gaming capabilities that allow for an influx of multiplatform games seperate from the Wii which is not placed in the same category. It is such a dicotomy that both the 360 and PS3 have been bundled together to explain this environment that developers see when it comes to making games.
The generation portion seems to be the result of confusion throughout the community and some unfair classification off the Wii and Wii U as a result of their hardware strength positioning.
Casual and hardcore while used by individuals with ill intent, is an exceptable term to identify a persons involvement in an activity. There is such a thing as a casual sports fan, exactly as you described it. Identifying games as casual or hardcore has been used loosely, it identifies the perceived target market. I don't see mainstream as an exceptable replacement term as that has different indications that don't describe what is trying to be conveyed. Again this seems to be the result of misuse and confusion.
The term fanboy can go away though, should just call people gamers or fans.
Before the PS3 everyone was nice to me :(
