Sequels X4 oppertunity, random idea (dont take to serious)

So im bored and class and realised a great marketing idea for X4, X-men F4 team up, since fox owns both. Figured it could also fit great with Xavier being in another body.... throw in shadow king, and mix up the Onslaut story a little by some how having him be responsible for the creation of onslaught by kidnaping franklin richards (of course this movie would have to be after FF3, and would be the 4th movie for both franchises in one) sure id like them to each have there individual 4ths, but hey think this kinda works too