It's plausible, and highly probable, that these shows will be back on the air within the next few months or years, but the news is still pretty bad for the fans. There's absolutely no guarantee that their favorite show will ever be on the air after this; Everything is depending on each series maintaining a high enough popularity to warrant future episodes.
But a thought has crossed my mind, and I know it's hopelessly optimistic, but it would just be too great if it was true. What if this is a sort of experiment with seasonal TV shows? What if they are pulling long running shows off of the air in order to give their manga series a bit of a headway, that will later be used to give the show filler-free chunks (seasons) of episodes? That's not how things typically happen on Japanese airwaves, but it has has happened before. Bakuman seems to be thriving in it's seasonal rotation; It gets 26 filler free episodes a year, from what I know on the subject.
If my optimism turned out to be the case, it would definitely be an occasion for fans to rejoice for filler-free, well-paced episode adaptations of their favorite manga series.
For now though, the future of these shows is unfortunately vague. Beelzebub, Bleach, Gintama, See you later, Space Cowboys.