It's more than likely that the old system will never come back. Despite ppv2's flaws, ppv1's biggest problem was the emphasis on PP in relative ranks on scoreboards, giving more emphasis to getting a higher score in the rankings and not necessarily the map's contents itself. There's a lot more, but that's down the rabbit hole of those discussions.
On the flipside, I don't believe ppv2 is being actively worked upon from this point either. Any proposal for a new system would need to be thought upon ourselves, or some farsighted thought towards osu!next.