They should call the redesign the 2DS, droping the 3D screen altogether. This will appeal to potential buyers that do not like the 3D and can't justify buying a system that is called "3DS" only to play it in 2D. This will both drop the cost and increase the battery life. It can be marketed to show the value of all the other features besides the 3D.
As far as time frame, I think it should be ASAP. It should be more of a second tier than a redesign, kind of like what sony is doing with the NGP, having a version with and without the 3G.







