It's an interesting topic but regardless of what is taught in school, conforming to heterosexuality is always going to be seen as the 'right' thing to do for younger kids. On the other hand, I do agree that in general, kids aren't as judgmental as teenagers or adults.
On the topic of being 'taught' to be sensitive, I recall when I was 7 and I used that old saying "easy peasy japaneasy" and my teacher said it was racist and that we should say "easy peasy lemon-squeasy" instead. I do think it's important for kids to be taught to have an open mind but they are going to pick up on what is said in passing in their environment.
In terms of homosexuality in the future, I think it's pretty safe to assume that much like the race issue, people are slowly going to accept us as normal. Of course this is just my opinion