I was there one week ago, it was still closed with no reason to think things would change soon.
I second the idea of approaching via Unknown Pond, the views of and from the Horn are well worth it. The shortest approach to Cabot is currently from Mill Brook Rd (via Unknown Pond), but if you start from York Pond Rd you can make a nice loop using the Unknown Pond and Bunnell Notch trails. Keep in mind the bridge at the hatchery on York Pond Rd is still out, so the loop is about 15.5 miles (vs 10 miles for the Mill Brook up-and-back).