Before Paige was announced as the new SmackDown GM, Carmella cashed in her MITB briefcase and Samoa Joe returned to challenge Roman Reigns on Raw, all three of those names were pencilled in as ideal candidates for a shift during the Superstar Shakeup.
Others, like Charlotte Flair, Asuka and The Miz were also considered, but there's unfinished business for all on their current brands.
It's important that WWE use this Shakeup as an excuse to heighten the difference in presentation between Raw and SmackDown. Both, as separate brands, should have separate identities; the chance to turn SmackDown into the finest wrestling show around is staring them straight in the face, and that dynamic would only help Raw's own soap-opera feel stand out.
Post-WrestleMania is a notoriously tricky time for WWE. They must be mindful then, to take advantage of huge matches that would carry them through until SummerSlam and make the changes to personnel that'd reignite careers...