RR was not even a flop imo. It just looks like a flop because she was so huge with GGGB.
And yes i think Gaga can recover ( maybe American Life > COADF) if she releases music that the GP like (not Dance-Pop tho) and with the right marketing strategy i believe she can sell like BEYONCÉ did and have 2-3 Top Ten Hits maybe 1 Number One single.
I don't really think she can get back at her peak. It's clear that she hates "The Fame" sound now. And it's songs like Bad Romance or Just Dance that helped her garner all the love from the general public.
I still remember all the straight guys in my high school singing "Bad Romance". Cute but creepy.