EPA has published a batch of proposed Significant New Use Rules (SNURs) modifications to loosen the restrictions on new uses of 24 PMN’d chemicals as a result of submissions of Significant New Use Notifications (SNUNs) that showed acceptable risks associated with the new uses. EPA is still holding on to some restrictions for all the chemicals, but sufficient information allowed these companies go beyond the original PMN/SNUR use conditions.
Interestingly, one of the original PMNs goes back as far as 1988! Several from the '90's and the most recent 2010. Did it take that long for new uses to develop, toxicity testing to be completed, enough money to be made under the original constraints and/or EPA to work through the SNUNs (earliest was 2003)?
Regardless, don't be afraid of developing new uses for SNUR'd chemicals - you can get SNUNs approved.
6/30/15 Update: Final rule with changes on 24 SNURs here