In a large bowl, add coleslaw, peaches, blueberries, corn, onion, basil, aged blue cheese and almonds; toss to combine. In a medium bowl, whisk together olive oil, 2 tablespoons white balsamic vinegar and pinch of kosher salt. Drizzle over slaw mixture and toss to coat; set aside.
Preheat grill or grill pan on stovetop to medium-high heat. Lightly grease grill. Season chicken with kosher salt and pepper. Grill chicken, flipping once, until no longer pink and juices run clear. Remove from heat; set aside.
During final minutes of grilling, in a small bowl, stir together peach preserves, brown mustard and 2 tablespoons white balsamic vinegar. Brush glaze over both sides of chicken. Transfer chicken to a large platter to rest; brush with any remaining glaze.
Stir coleslaw and spoon onto individual plates to serve. Add a chicken thigh to each plate and sprinkle with blue cheese.