I wish there would be new Dragon Ball series in development. If there is, I hope it won't continue where Z or GT left. As much I love the series, the power got a little out of control in my opinion and got a little tiring to watch.
I would totally be fine if there was completely new Dragon Ball, with new characters, that starts from the very beginning, like the original Dragon Ball. Hopefully Akira Toriyama would be behind the story.