Yeah, all those anime are indeed getting reboots, but that's because they hardly followed the original manga. The FMA anime couldn't be any more different from the manga without being an entirely new series, so they made Brotherhood; the exact same thing goes for Kenshin. The same can be said for Helsing, so on and so forth.
Dragon Ball, however, followed the manga extremely close, the only difference between the two being the filler (which was so expertly woven in that it's still difficult to tell the two apart) and a few minor aesthetic changes (in the manga Piccolo only has 4 fingers but in the anime he has 5 like a human). Going by the same logic most of these anime reboots have been following, there'd be no reason to make another Dragon Ball. Besides, Dragon Ball Kai was supposed to be the reboot anyway.
Add to that, if we do see another series it would just be done by Toei Animation. The only involvement Akira Toriyama would have with it would be giving permission to Toei to make it. Toriyama stopped caring about DB after the Frieza Saga (by his own admission), which is the main reason he didn't do GT; he desperately wanted to move on and finish the series, but his publishers pretty much forced him to keep writing more. When it came time for GT, he got out as fast as he could. The biggest thing people hated about GT is that "oooooh, it's not canon because Toriyama didn't write it" and all that, so unless people can get over the fact that Toriyama vomits every time he sees DB because it's been rammed down his throat so much, I doubt a new series would go over too well.
I'm happy by the main series being kept alive by the video games and random fan mangas and OVAs that pop up occasionally. While a new series would be kinda cool at first, I think it'd get old fast among fans. Only the hardest core fans would stick along, and it wouldn't be enough to fund the anime.