If I had to post my predictions for the future, I would have to say Dragon Ball Z Kai will replace Attack on Titan and Toonami might get a deal to run the new Sailor Moon dub in place of Bleach. Now, before you all explode and say "Nope, can't run that, it's before Bebop." here me out.
From what I am reading, Dragon Ball Z Kai is a remastered and revised cut of the original DBZ, made to follow more closely to the manga. So essentially, it's Dragon Ball Z (which pre-dates Bebop), just a director's cut. While the new Sailor Moon dub doesn't have any changes in, it is still revised in a way. Toonami ran the original SM dub (which as you all know was heavily edited and it completely omitted several episodes, as well as skipping over Sailor Stars). This is a brand new uncut dub that will showcase all 200 episodes, as I'm sure you're all aware as well. This is why I believe it is an exception to the "nothing older than Bebop" rule.
Some additional thoughts:
*I have heard that both Attack on Titan and Bleach will finish on the same exact night. Now, wouldn't it be a great decision for Toonami to have 2 of their most popular series return on the same night?
*The already-mentioned newly dubbed Sailor Stars season (an entire series never aired in America)
*Bleach and Sailor Moon are both Viz shows, Attack on Titan and DBZ Kai are both Funi shows. Since that seems to be how the block has been replacing their shows as of late, wouldn't it make sense to bring in a popular Viz and popular Funi show to replace two other popular Viz and Funi shows?
*Viz Media is clearly open to a TV deal, as sourced by a ToonZone interview
*The Toonami crew, in their Manipulating The Manual bump, they asked the question, "Should we go more nostalgic?" That line makes it seem that they are open to airing past Toonami shows (I'm not sure if the nothing older than Bebop rule applies to that, but the point still stands).