Yeah, given that we know that JKR likes to have names that correspond to their characters (Sirius turns into a dog...Lupin is a werewolf...Lestrange is, well, strange...to name a few), I think that there is absolutely no chance that a boy named A.S.P. is not going in to Slytherin. I think that, having read seven of these books and knowing how she thinks by now as we do, that it is quite frankly canon that Albus Severus is a Slytherin.
As for Rose, I figure that either she or her brother ends up in Ravenclaw, and the other in Gryffindor, and which one goes where depends on what kind of characterization one chooses to give each. I don't mind which Granger-Weasley goes into which house, so long as one goes into each. I think that one of Hermione's kids just has to be a Ravenclaw.
I do think that most of the other Weasleys end up in Gryffindor, but I don't think all of them. (For instance, I like popping all three of the Delecour-Weasleys into Ravenclaw, and letting them be pretty little charming bookworm flirts whom you do not want to meet with a Beater's Bat in their hands. )
As to Scorpius, he's a Slytherin. Absolutely. I've seen some Ravenclaw Scorpiuses (Scorpii?) that work all right, but I prefer him as a Slytherin. Scorpius is still a Malfoy, thank you very much. He's not going to be the arrogant little brat his father was, not after everything that Draco went through, and his whole "raised his son to be a better man than he was" thing...but he's still going to be a Slytherin, I think. (Besides, then he and Albus get to be BFF!) Certainly he's going to expect to be in Slytherin, and want to be; it's a matter of family honor which, I feel, is very important to Scorpius. I know we get pretty much no details from the epilogue, but just given the very brief description we do have, I feel like Scorpius is close to his parents, and wants to live up to what they expect of him, which in his head is going to have to include Slytherin. (Besides, there's that whole "raised his son to be a better man than he was" thing again -- obviously Scorpius is going to feel some pressure of expectations, no matter how much his dad tries to hide that. I'm seeing an earnest little overachiever who is continually competing with Rose for top grades in the year. And poor Albus stuck in the middle!) And I like having them both as Chasers, because then they get to play together instead of competing. But, you know, whatever works for whichever story one is telling at the moment!
And Teddy should definitely be a Hufflepuff. Yes. ;D The best Hufflepuff ever!