Oh I think that's a given. Noone is gonna upgrade if they can't take their vast collection of toys with them. Even if Poser 5 does abandon the .CR2 (unlikely, I would think) provisions will most assuredly be made for conversions. The library files (and geometry files as well) that Poser reads are, at their core, plain ASCII text that get interpreted by the program at runtime. They read like an insctuction sheet, or oddly constucted grocery list. They would have to go out of there way to make them non-compatible.