I don't know why people act as if this makes Cena/Undertaker any more plausible. Undertaker has said in interviews that Brock Lesnar is the one opponent he'd love more than any other to face at Wrestlemania at this point, so with Lesnar apparently freed up from facing The Rock (at the moment, don't get too optimistic just yet, it's still several months till Wrestlemania), that could just mean he's facing The Dead Man. I can think of several different possibilities for all the main players (Cena, Bryan, Orton, HHH, Lesnar, Taker, Punk) going forward into the event, though.
I'm really glad as hell Rock could be missing next year's event, though. I'm a Rock mark, but his return hasn't been quite as good as I had hoped and I'm already tired of him. We've had Rock either heavily involved in the build or wrestling in the match itself for the last three years and I'm ready to see something different for a change.