I tend to not put much wait into the type of screenings that are given for really young kids - but I'm also guessing that between genetics and what you've seen so far, chances are your ds is gifted and will very likely qualify for the school you're looking into when he's older.
My question is - if you like this school and want your ds to attend, does it matter if he doesn't get into elementary school there later on? Is your concern that he will be going to a new school with new friends? If that's your concern, I wouldn't worry much about it - many many kids make a transition to a different elementary school from preschool and it works out a-ok - it did for all three of my kids.
Best wishes,
polarbear
