Anything can happen man, you can really judge success you will have in highschool compared to times you run in middle school. I know plenty of guys who come into highschool with very fast times as 8th graders but don't improve much but still make it down to 4:20, and I know just as many guys who don't come into highschool with fast middle school times and make it down to 4:20. It's all about the dedication,determination,hard work and smart training. Just focus on doing that and the times you want will come.