I have a little extra info on this: I spoke to the Remington rep at the Ellett Bros. show (kind of a mini SHOT show). Regarding Marlin, he grimaced and said they were trying to get all their production issues resolved. For those not "in the business", quality of Marlin lever guns took a serious dive after Remington bought the company, uprooted it and handed it over to a bunch of new, untrained workers. We (the store I work at) sent back close to 75% of the Marlin centerfire lever guns that we had come through the store after Remington took them over. Problems ranged from absolutely horrible wood to metal fit, to actions so rough and stiff that King Kong couldn't work the lever, to guns that wouldn't even chamber a factory load. It was horrible. We got to the point that we wouldn't even special order any Marlins because we knew we would receive a P.O.S. that we couldn't sell.
At any rate, the Remington rep acknowledged all the problems Marlin was having and said in order to help resolve the issues, they were going to streamline Marlin's line and were, for the immediate future, going to focus on the more popular models/calibers. He didn't say with 100% certainty that the .338, .444 & .450 would be brought back but he did say that they hoped to be able to restore Marlin's line to what it was prior to Remington taking them over, AFTER they got all their production issues resolved and got once they got their new staff PROPERLY TRAINED. I would think you would train your staff BEFORE you turned them loose with a bunch of parts but hey, that's just my thinking! Anyway, HOPEFULLY we'll see these cartridges reinstated in the line at some point, probably not in 2012 though...