Well Earthquake is one I figured might gain some additional popularity since it does get around it, but that's not being reprinted so it's only in until Scars (unless they reprint it there)
Basically though it takes away the straight up "burn their face" option though Searing Blaze/Bolt/Burst Lightning/Staggershock, etc.
Combined with the fact that U/W decks will probably be maindecking Mana Leak and continue running spot removal (Condemn) and sweepers I think it'll be hard for RDW to put up much of a fight with the Leyline in play.
Plus I think if you're bringing in 4 red leylines, and 4 earthquakes it has the potential to really lower your threat density as well; even worse if you plan to bring in 3-4 Combust to deal with possible Baneslayers and Colonnades/Walls. Sure the red leyline stops the lifegain but a first striking 5/5 that takes at least 2 spells to kill can still be a problem.
I dunno, I guess I had high hopes for RDW during 90% of the spoilers and after seeing the white leyline, can't really imagine it being overly competitive. It did get some nice cards and a few answers but overall I think most of the other colors got more. Guess we'll see after the release.