I think so. The Nitto rep I met last year told me they would be but didn't give me a time frame. I checked the Nitto site yesterday and they were there. I checked again today and their site has been updated and the R2 is gone. Let's hope they start making more NT01's in the 305/35/18 going forward.
New
http://www.nittotire.com/race-tires/nt01-dot-compliant-competition-road-course-tire/
Gone
https://www.nittotire.com/Tire/Competition/nt555r2
New
http://www.nittotire.com/race-tires/nt01-dot-compliant-competition-road-course-tire/
Gone
https://www.nittotire.com/Tire/Competition/nt555r2