Why Jennifer Lopez and Steven Tyler BOTH Left "Idol"

Steven Tyler and Jennifer Lopez have both announced they're leaving "American Idol" after just two seasons.
Lopez announced her decision by calling Ryan Seacrest on his radio show on July 13th.
She told Ryan, "Something had to give, something has to give. I was really dreading this phone call with you. I honestly feel the time has come that I have to get back to doing the other things that you do, and you have to pay attention to that, too. I could keep doing Idol for the rest of my life, but that would be giving up a bunch of other things. I feel like we had an amazing run."
Steven decided to leave the hit show because he wanted to focus on his music,"I've decided it's time for me to let go of my mistress American Idol before she boils my rabbit. I strayed from my first love, Aerosmith, and I'm back - but instead of begging on my hands and knees, I've got two fists in the air and I'm kicking the door open with my band."
Who do you think will replace the two judges on the show?