I think even when the game is back to it's full glory, we won't get much new content, if any at all. There IS an un-used country south of the Majin starter land, so potentially lvl70~lvl75 could be done there with some generic quests, but even THAT would require a lot more effort than you think.(Just think of all the new weapons, quests and armor he'd need to make.)
If Daneos REALLY wants to, he can try to increase the level cap, but personally I'd rather see the game become more stable, return-to-form DBO first, and maybe then receive some effort in balancing everything out. The PvP in the old DBO is incredibly one-sided, for example. Whoever lands the first stun/sleep/paralyze wins, assuming they have good attack gear. There's never much of a "fight" going on, unlike in earlier level duels.
In ranked battles, you never start with RP or any buffs, removing alot of strategy in those fights. Most buffs are only useful in free duels or on the PvP platform, where the winner doesn't matter anyway.
And a lot of skills and even transformations were either completely useless, OR completely overpowered.(Kaioken x4, looking at you.) This forces a lot of players to be one-trick ponies.
So even if Daneos manages to succeed in bringing back the old DBO entirely, there is still a LOT to be done. Increasing the levelcap doesn't help him with anything at all. If he DOES do it, he's either lost his mind, or we're 3 years further.