I don't think they have a que, per say, like that. I think that different teams work on multiple things at the same time. Like, I don't think EVERYBODY in the rework team is working on skarner; that's one or two people.
So, the gangplank rework will come around when it comes around. It may have been set aside temporarily in favor of more pressing things, but I doubt it's been forgotten.
If you want to talk about riot's timetable, I think that's an issue, too, but not the same issue.
edit: @Devs, if you're reading this. I don't think that there's a problem with the timetable, per say, just with the communication. Solution: DEV BLOGS (Rito pls more). I'd love to know things like "We're in the middle of reworking gankplank. So far we tried giving him a new w and e, but that didn't work because it didn't feel like gangplank anymore (no oranges), so now we're experimenting with combining w and e into one abiity." It doesn't need to be long, but it's just nice (to know what you're working on) and interesting to hear what you're working on.
TL;DR more frequent, short, "check-in" posts would be nice.