As I recall, one of the prerelease blurbs on paragon paths mentioned something about some of the paths were planned explicitly for multiclassing characters. I suspect that they were cut for either page count or insufficient design time reasons. I think that we will eventually see at least one paragon path for each class option, much in the same way that we're seeing racial paragon paths in the warforged Dragon article. The paragon multiclass path would presumably give a basic class feature of the original class (or something very similar) as the 11th level path ability, another class feature at 16th level and then perhaps allow you to pick any encounter, utility or daily power from the other class of any level lower than your current level for your path powers at 11th, 12th and 20th level. Not sure what they would do about the action point feature, since that's not really standard to classes.