One of my three children is significantly less academically-inclined than the rest of the family. I think it's natural to have a little bit of trouble coming to terms with it, if your intellectual abilities are a large part of your identity (which tends to happen if it's what makes you unusual), so don't beat yourself up. The extreme amount of love you have for your child makes it a lot easier! From my perspective, it's helped me to appreciate that people can have astonishing gifts without being good at taking tests or without being able to learn things super quickly. I am just as amazed by that kid as the other ones (he is hilarious, thoughtful, passionate, hard-working, creative... I could go on!). And my other two kids have learned the same thing from the beginning.
But you can imagine that my kid's experience has been difficult. Kids naturally compare themselves to their siblings. That part definitely sucks.
Anyway, all that being said, I agree with everybody else that it's too soon to tell with your kid!