Jeff I was an only child in the middle of nowhere and we moved out there when I was 6. I did however got to a public school with kids my age and participated in many activities, birthday parties and such. I also ever so often went over to my friends or my friends came over for the day (and when that happened the bonus was we all went into the woods to check my minnow traps and run wild). This is much the same way we raised our 2 girls although even more difficult as they went and are going to a magnet school outside the area they live in so their friends are from all over the county and not a few miles away. It is difficult on children (even with 2 they don't always play well together) not having someone to play with on demand however having woods and such to run (especially for a boy) and room to have special places to play unlike the city (my girls loved having room to run) makes up for it. Looking back on my life which mirrors the situation you are talking about I would not have traded where and how I was raised for a life surrounded with kids every day. In fact I think living how I did and having to entertain myself versus having others to have fun with has helped me be a lot more creative in solving problems than others raised in town or the city. Now today is not the same as it was when I was growing up and people across the world connect with each other on a daily basis. Looking at my girls' case they have the internet (which I did not) and are able to interact with their friends from school daily after school and weekends. In fact the other day my oldest was playing a game with her best friend who lives like 20 miles away. They had voice chat going and were talking and laughing with each other as they played which in truth is more than I see them do when together in real life. In fact they are somewhat reserved, shy, and quiet in person. She also the same weekend drove to meet her boyfriend (about 25 miles) and went shopping and to the movies (which is similar to doing the same with friend when she was younger although we provided transportation back then). It is a bit harder living out here on my youngest because she is somewhat a social butterfly however she even says she would not trade having friends around her for the simple joys of living out here and having her chickens, ducks, garden, and wildlife.
The key is providing chances for your child to interact with other children while at the same time them knowing this is not an everyday thing because we do not live close to them. You also must provide things (not I did not say toys) to do to keep themselves entertained. When my girls were younger I put lag bolts into a big oak tree like stairs and hung a rope so they could climb into the branches. The oldest built her a "nest" one summer and spent a lot of time reading and enjoying nature in it. The youngest preferred being in her hidden "garden" under the bushes. Both relied heavily for entertainment on something I think a lot of kids these days do not use and that is their imagination.
I will say it is going to be a big adjustment but he is still young and able to make it and in fact will most likely love it. If he were say 11 or 12 it might be harder especially being the new kid at school.