I have not expirianced this, but here's my opinion.
Grades are not allways important. As long as you have c+, you should be fine. You may not be able to get in a great college, but if this talent of yours is as promising and it is pramoted to be, then i would continue the hobby. The only flaw i see here is that if you cant get into a good college, you might not be able to use yours computer skills.