Than gain, Omega Red is possibly in it, so I wouldnt be surprised if ratner starts chucking out the cash to hire Tobey, Ioan, Chris, Jessica, Tom and anyone else who's played a Marvel character... next we'll have Tom Cruise as Yukio!!!!!!!!!!!!!!!
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Thanks to Badwolf for the great sig!
Most fans are expecting a huge redemption at the end of X3. I don't think she's necessarily gonna "lose" her Phoenix persona and "go back" to how she was, though. The Phoenix is a part of her evolution. Jean is the Phoenix and the Phoenix is Jean. They're one and the same.
Most likely, it's just gonna be Jean "calming down", by the help of Logan, or...ya know....Scott. Either that, or she has to kill herself just like in the comics.
As to your second question, yes, it was the Phoenix reflection we saw under the lake at the end of X2.
And no, the Blob is not in the movie. Or at least, nobody's making a big deal about it. No newsflash or whatever, but who knows, he might be a blink-and-miss cameo.
Alan Cumming didn't turn down the Nightcrawler role. In fact, months before the shooting, he adjusted his schedule to make way for the X3 production. However, he wasn't asked to be back. Apparently, there are too many mutants to explore in X3 already, and his character arc was already completed in X2 anyway. It would be a waste of his character if he's just gonna stand around in X3 being all eye-candy but really useless to the plot itself.
Also, Alan Cumming was fine that he wasn't asked back because he found the make-up process a pain in the ass.
If they make an X4 they should throw in the Blob. Who might you ask should play him? Oh, its simple...by far the simplest casting decision out there...Ethan Suplee.