From the TVGuide interview before the finale:
So Addison dipped her toes in the happiness pool with finally getting with Sam. Therefore, I take it means she will be full-on swimming in the happiness pool next season with Sam.
"She might put one foot down on the road to happiness," adds Walsh. "Like she dips her toes in the happiness pool, so hopefully in the fall she'll be full-on swimming in happiness."
After 5 seasons and so many dead ships, I just want to see Addison in a stable relationship for once. I hope it is with Sam because starting another new relationship at this point just seems silly. Of course, there will be drama, but I just want the endgame relationship. I see PP lasting for another season and quite possibly to season 5 (for syndication purposes). After five seasons of being tortured, I want one/two (depending on a season 5) seasons of a mostly Happy Addison in a stable relationship and hopefully having a baby or adopting. I don't want her happy ending to be a "blink and ya miss it" kinda thing.