Kylie however I can still see her being appealing to the teens as she is a MILF and is capable of releasing something modern and it doing well, her on a typical Calvin Harris track would do well & Jay Z is writting her new album who I believe makes Rihanna's albums?
Kylie isn't fully dated yet she is still marketable if you get the right sound just like Britney who scored a no1 in early 2012 with will.i.am and a recent top 10 hit here with Work Bitch, which would of git a top 3 spot if was promoted here (she didn't perform the song here which impacted he chart placement, if on X a Factor it would of got to no1 prob.)
its funny you should mention rihanna, because in her short career she has managed to outsell kylie in terms of single sales already in the uk.
rihanna has been very current in recent years and naturally, many people have imitated her, but personally, i wouldn't want kylie to follow suit.
i very much doubt that britney could have got to #1 with "work b**ch" though, as it was too similar to her previous smash with will.i.am, which got to #1 in 2013 btw.
i really don't think her supposed "milf" status will count for much if radio don't support her and like you observed with cher, kylie will also need support from all the major radio stations to succeed.