What would have happened if Dende could have made new Dragon Balls? This is of coarse a hypothetical question cause I do know that he needed to make the old ones reappear in order to do the thing with Cell. But this is only part of the question if Dende created new balls would the seven Dragons appear? I think not because there should be no negative energy in the new balls but im curious.
It would take longer, but they would appear eventually. Humans would keep on wishing for stuff, adding to the negative energy stored in the balls. So I guess they could renew the balls from time to time, preventing the negative energy from building up, but where would the energy go and what would happen to the balls? The negative energy is still around, so I think even if the balls would be renewed over and over again, the cumulative negative energy would eventually make the seven dragons appear. I think it was Earth's destiny for it to happen. We should all be happy that at that exact time, Goku was coincidentally strong enough to defeat them. Imagine what would have happened if he was still only a boy.