I don;t know for sure. But if you look at the trends- EB1 was never retrogressed. In Oct 2005 DOS overestimated and retrogressed every category. This happened because-
The DOL and USCIS were not processing a lot of case so EB3 was current for whole world. Due to this the unused visa no. from each category were transferred to India and China. Early in 2005 EB3 rest of world retrogressed. Due to this DOS will transfer unused no of EB1 and EB2 to EB3 in same country. So in Oct 2005 DOS overestimated the dates but the forward movement was very fast about 6 months every month.
Even if EB1 will retrogress, it will only retrogress few months. Not like EB2 and EB3. EB2 from India is retrogressed because of most of computer professionals are eligible for EB2 because of work experience.