But Rowling is clearly implying that Albus WOULD be in Slytherin, actually. First he makes ongoing comments about the house, then he is seen in GREEN robes during the Quidditch world cup, while the rest of Potter family sports RED. Those are little implications or foreshadowings og him being placed in Slytherin, in my opinion.
Yeah, that's kind of what I thought too. I like the idea of Al being in Slytherin; I imagine him as the "black sheep" of the family (his name alone makes him stand out) and inherited Harry's Slytherin traits.
I don´t see him as a black sheep at all; black sheeps are people who are usually disliked by their family. I think that the Potters love Al but they see he is different, but the Weasleys might be more sceptical of his character because of him possibly making it in the Slytherin house. The Weasley have been always more prejuiced, especially when it came to Slytherins. I think they would still love Albus; they would probably act a bit differently to him, though.
I always thought black sheep was just someone that stood out or was different (they can be disliked but not necessarily) I think Al is loved by his family, he's just different (I think James would be a little mean to Al but that's because he's the older brother, he loves him but enjoys picking on him because that's what older brothers do, plus he seems kind of like a brat.) Percy was a black sheep in his family and they loved him but they still picked on him because he was different and they thought he was boring and bossy. The Weasleys seem pretty prejudice against Slytherin, at least from what Ron said in the beginning, which being 11 he probably learned it from the rest of his family. It's one thing that bothers me about Ron, there are a lot of Harry being in Slytherin stories where Ron hates or at least ignores Harry just because he's Slytherin, which sadly I find believable. It wonder how Ron would react if he knew that Harry had nearly been placed in Slytherin.
But Harry WAS nearly placed in Slytherin! It does not matter, though. He ended up in Gryffindor. Had Harry really become a Slytherin, though, Ron would have not liked him at all. Which says something about his character, right? Out of the main trio, only Ron was a prejudiced asshole.
So I bet he would get significantly colder towards little Albus, if he really became a Snake. At least from the beginning. But Hermione would MAKE him change his ways, I guess. Hemione was, due to her Muggle-born status, very understanding towards all people who were different.
The rest of the family would pity Harry for having a Slytherin child and even Albus for getting in the house of Snakes, at least at first; but they would gradually make up their minds about the whole house hate and rivalry ´cause it really does not matter. Grandma Molly (Weasley) would be the first to stop the hate. She KNOWS what Albus is REALLY like. And so does the rest of the Weasley family.
They WOULD be wondering, though, how is it possible that Al was sorted in Slytherin. They would try to dissect his character while he was not at home and talk about him possibly hiding some "evil" Slytherin qualities they have not noticed before.
You know, it is APPARENT that little James Sirius does not tease his brother Albus about Slytherin for NO reason. It MIGHT be just an unbiased childish teasing about "the evil house that makes you go really baaaaad" (children in general love to tease other children to make them cry or angry - just for the fun), but it seems that at least Harry (if not Ginny) has been raising their three kids with an open mind and a no-hate attitude towards all Hogwarts houses.
This means that the kids logically CANNOT feel the same level of anxiety about Slytherin that their father had felt in his childhood. Yes, Albus is anxious about it, but he seems to be an anxious child in general. And Harry seems OK with Al possibly being a Slytherin. Not happy, but OK. No hate there. Which means that he has previously THOUGHT about the possibility of Albus being a Slytherin - like little James! He apparently teased Al with Slytherin because he must have OBSERVED some non-Gryffindor behavior in Albus. And because Albus did not seem very brave or extremely smart (I am not saying he´s stupid, though!), I bet he WILL end up in either Hufflepuff or Slytherin.
So James must have OBSERVED some Slytherin behavior in Albus we had no chance to see. I thought it was rather logical! James is not stupid. He is a Gryffindor through and through, and that is why he can easily see who is like him and who is not. Albus is close friends with Rose, who is a Hermione-type-of-a-bookworm, which means he is rather cerebral and less sporty than James, who is a prototype of a jock (even though it is apparent that Albus is into Quidditch as much as James, Ginny and Harry). So generally, as it was seen, Albus´ disposition is rather quiet and thoughtful. And Gryffindors are all loud and often rude. You know, Albus does not have the middle name (Severus) for no reason. That would not be Rowling.