It's hard to say really. I've had so many kids i've worked with over the years.
In my experience, the kids who can't find or make friends (even with a lot of work on your part) are the kids who have the problems later on in life.
There is always a place for the kids who's minds work differently. If you really pay attention, you can find the other kids who think like your kid. Maybe the quirky kid is a music genius, or artistically inclined, or loves dance. Maybe he or she is a math geek, and a chess club would be his niche. Maybe you just need to find his "People".
I've run across a few kids who I thought would be diagnosed with Aspergers or (at that time, it was called Pervasive developmental disorder) But, it turned out they were just not the average kid, and once they got involved in something, they seemed to blossom. J has always obsessed over something... at first it was Thomas the Train, then Rescue heroes, then bibles, then eventually he discovered Marching band. Now he has a full ride college scholarship to a state college. He's the Drum Major (most important part of a band) and he's 1st chair sax in his college Jazz band. He was the quirky, weird kid who is now wildly successful.
Ricky was a hard kid. I thought for sure he'd spend most of his life in the back of the class licking the wallpaper. He's 30 years old, and runs a large Comic company on the East coast. He's a gamer, comic, genius. (Never saw that coming)
But, some of the kids I was concerned about, did have problems. The ones who went undiagnosed until grade school have the most problems, but all have devoted parents and a support group to help them.