"adapting" the DP Saga during X3 is a little generous. It was the D-plot in a movie with like eight of them. No DP Saga will ever be successful without two things: Build up to it, and have it be the primary focus.
For it to work you need it to be a trilogy after you've established your core X-team. Part one is the emergence of Phoenix and learning of the Shi'Ar. Part two is the M'Kraan Crystal arc. Part three is Hellfire Club and battle for Jean. There has to a level of gravitas to Jean going Dark. We need to see how powerful the Phoenix truly is in order to get a sense of scale when Jean goes dark and the raised stakes.