So, at present, we know about several upcoming or current writing teams on a book, etc. Tynion IV is working with Snyder on Talon for the first arc, Giffen is going to join Levitz on LoSH, Nicieza is scripting for Lobdell on TT for probably as long as the H'el and DotF crossovers at least, Fawkes is joining Lemire on JLD, Goyer is going to be working on something big with Johns...
Most of those are pretty good moves. Talon is mainly Tynion's project but having Snyder write it with him makes his book sell better, Giffen and Levitz previously wrote the definitive LoSH run, Niceza's dialogue and exposition is better than Lobdell's, Lemire has too many projects to do JLD alone and has managed to bring in another indie writer, and Johns and Goyer's prior work on JSA is well-acclaimed (can't speak further, haven't read it ). Sometimes a second writer can add a lot that one wouldn't have thought of, or be the person to point out what won't work, so I thought it raises an interesting question. What titles do you think could do with gaining a new writer and yet still not getting rid off the first?
I'll throw out a couple suggestions.
Earth 2. Robinson probably needs someone else to script for him at this point, I think enough people can see there are issues with the dialogue, despite whether it personally takes you out of the story or not.
Nightwing. Kyle Higgins writes Dick really well and gets his voice perfectly, but his stories haven't really been that special, or they're just rather reliant on Snyder's work. I'd rather see Higgins focusing mainly on the script at this point while someone else does the actual story ideas.