Wouldn't mind if Toriyama did something with the evil dragon plot theme but I'm almost sure he won't. He designed an entire new char + new plotdevice for vegito just because they used gogeta in the film earlier than he could use him in the show. He's quite keen on him showing his stuff or ideas first. So I assume any GT ideas are probably off the map for this.
I think expanding upon the Gods is some of the coolest stuff. It'd also be nice if he gave the dragonballs more lore, possibly even involved the namekians again. I mean, how DO they create these things? Maybe they're not namekian at all but just a race who it was taught to. Perhaps the first dragonballs were made by a God. I think there's great stuff to do with what he brought in in terms of lore with BoG and without spoiling anything the end of RoF does seem to hint at what might be to come.
Really hope the series is post-RoF, with a teen/adult Trunks And what somebody else said, was that you Ang? Or Adeno? About designing plots that don't involve rendering everyone but goku and vegeta largely useless. Toriyama needs to watch the JL TAS.