Just skimmed this because I reeeeeally need to go to bed like, 10 min ago, but I just had to say regarding intertwining fandoms that this actually still definitely do exists, but seems to be more common with genre shows and particularly young adult-aimed such. I have seen many an article comparing Elena/Bella/Sookie/Buffy/Katniss etc, for example, plus there's the natural comparison within different versions of the same fandom (Sherlock being the most obvious one)... It's around, is my point, but maybe you're right in that it doesn't bounce between the fandom as much, like maybe it's mostly people on the outside of fandoms doing the comparing.
I have more thoughts on this, but: BED! Will return tomorrow!