Ballads doing better than upbeat "generic" songs if released as a single, for example some Kats really think It Takes Two would do better than This Is How We Do.
Beyonce is far overrated, the GP does not care about Gaga nearly as much as her stans believe, Britney's career won't make a comeback (no matter how much I want it to), and artists with moderate success that have plateau'd for a while (Austin Mahone, Fifth Harmony, Lana, Cher Lloyd) will never become HUGE artists (again, no matter how much I want them to).
I don't like any of the artists you mentioned but You are a perfect example of popular opinions that don't make sense, predicting the future is the most embarrassing thing ATRL people do :/
While I will admit that Gaga has some huge dance hits, dance has been in the mainstream for years so Gaga couldn't have brought something that already existed.
Music that you can dance to has always been in the mainstream, but this specific wave of euro/electropop/club dance music seemed to boom with Gaga (big explosive choruses, big beats, big synths, etc). The dance-y stuff that was prominent in 2007 was more urban-esque. That's why I'm saying I don't think she introduced it, but she was a huge factor in its progression.
A lot of people (many DJs) give her credit for that.
I disagree with:
Iggy being a good rapper and she shouldn't be deported
Bionic is a bad album that isn't filled with bops
Selena Gomez has released a good song
Ultraviolence is even a decent album
That the GP are really here for P!nk
Rated R is better than TTT or GGGB
That Christina and Gaga won't make comebacks