A new series with all the old DB characters... mehh...
Now something that might work... MIGHT work, would be a new anime that took place in the Dragonball universe, perhaps in the future or past, with all new characters. Like... maybe one taking place on the Saiyan homeworld Vegeta, before the Saiyans went extinct, showing their domination of the universe or something along those lines.
They did kind of remake DBZ in Japan by redoing it in HD, re-recording the voices, and cutting down all the fillers, so who knows what could come next. As the most popular anime/manga property of all time, I doubt Dragonball will die any time soon.
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