I think it is an improvement at least conceptually, which is a step in the right direction, and by formally tracking these we now have a better idea of how frequently new ones appear. During the past month we haven't had anyone serial posting such answers, which is where I think this mechanism will prove very effective one way or another.
To put a bit of perspective on things, we're averaging 1-2 posts per day added to the link-only chat room. This is a mixture of both new and old posts, found through a combination of flagging and moderators catching them first hand.
Of course, as you imply, what hasn't been happening is the questions getting actively fixed (so it clearly isn't a motivator for the OP, but that's predictable considering how little effort was put in initially). I just went back and did some from the past week, spending <5 min on each one that I did edit, but skipping about half of them because in my opinion they were not worth my time (e.g., links to youtube videos for solutions the OP "did not try personally").
That raises the issue of whether moderators should in some cases decide to just delete or (perhaps preferably) convert to comment after the 48 hours is up. I think this is not a bad idea for things that are almost certain to remain link-only and were borderline suggestions to start with.
One thing I would definitely suggest is that we divide the chat room into two. The "first stage" chat room would be the 48 hour holding pen. Part of the reason for this is the way moderators ended up dealing with things is initially posting just a link, which in chat expands to a precis. However, if there is anything beyond just a link in a chat post, there is no precis, and in order to track what's been dealt with after 48 hours, we've been going back and adding "done". That's expedient since you cannot insert chat posts out of chronological order, but it may be a discouragement to anyone who's in the mood to clean up posts, since from just a raw link it is hard to tell what the actual question is, etc.
Also, a concern I had in the original post about this is that most people probably won't want to bother until the 48 hours is up anyway -- especially since a major reason for doing this is to allow ease of editing via the lower bar on "Community Wiki" posts.
So, to sum up that suggestion, we divide the current chat room in two:
One, the 48 hour holding pen, can be moderator access only to prevent confusion, since it isn't of general interest.
The other can be world readable. When the conversion to Community Wiki is done, a moderator can then just delete/modify/whatever the post in the holding pen, then add a new link only post (creating a permanent precis) to the world readable "Link Only Answers" chat room.