If you've read the books and saw hoe the first season ended, this comes as no suprise! By skipping the two girl children they had in the books and immediately having a boy, it brought an end to that "we must have a boy heir" storyline that would have taken place in the second and third books.

Also the focus has to switch and it can't with him in it honestly. In addition whats the purpose of having him on the show in a reduced role? He's also already signed up for three movie projects over the next year.

I'm sure he'll return in future seasons but this next season ain't about him and Phoebe.