I'm not sure how much more of a plan we could have than what we have now. The Arborists have been amazingly successful in shrinking the backlog of pending merges, bringing it down from just over 30000 just 8 months ago to 6703 as of right now. And the oldest ones, the ones from the end of 2012, are all private ones, which can only be completed by a sysop (usually me). All I can say to that is, I'm working on it. :)
My hope is that once we're caught up on pending merges (which will be very soon!) we can shift some of our focus to the unmerged matches. Those take a lot longer since almost every one needs to be researched first, to sort out the problems that kept them from being merged in the first place.