The 30-year old star is taking some time off to assess his future and although Arena is confident he will be back, has made it clear that the back-to-back MLS champions will prepare without him for the time being.
"When he comes back, he comes back," Arena said. "I'm not going to worry about it. We're going to have a team ready to play come March 3, whether Landon's here or not.
"I don't know how long it's going to be. But we're going about our business. You lose players all the time: injuries, suspensions, [World Cup] qualifiers.
"A lot of things impact your ability to have all your players on the field at the same time. If this is another example, then so be it. And we'll get on with it."