Again, I haven't seen the PG edit of Naruto Shippuden on Disney XD, but I have heard some things about it. Keep in mind that what's being argued for is a rating below that.
The existing minor language like hell, damn, and bastard in Shippuden was cut. FUNimation One Piece has plenty of that, in addition to "s-borabs", "a-holes", and "sons-of-b's". It's a given that those would have to be cut to get on TV, but who knows what else would be cut for Y7?
Blood in Shippuden was cut. One Piece is full of blood and violence. There would be way too much of this cut for Y7, and that, more than anything, would really take away from the show.
In the beginning of the series in the Buggy arc, Nami uses her body as a distraction, later in the series in the Alabasta arc and in the movies (I know, we're not talking about those, just saying), her and Vivi show fanservice and are very bouncy, and Bon Clay shows off Nami's naked body, albeit with the naughty bits hidden, and much later in the series, more women are naked. That's a lot more sexuality than could ever be in anything on Nick.
By "Toonami One Piece", do you mean the years of 4KiRAB or the half-year of FUNi? The half-year of FUNi was PG, and of course I'd love to see the dub with that level of editing return to TV. If that didn't happen over two years ago, I wouldn't be on this forum at all. It's when you edit it back down another level to Y7, it gets to where 4KiRAB was, or at the very least, contains the problems I listed above.
But again, I'm not saying that One Piece on Nicktoons is impossible or even that I don't want it to happen. I'm just saying that it seems unlikely.
And wow, how the hell did I just write that much on something I don't really care about? Then again, with all the posts I've made about it in the rest of this thread, I guess I shouldn't be surprised anymore...