This is possible. If USCIS does not have enough approved EB2 applications to meet next year's spillover, the numbers will trickle down to EB3 (ROW).
However they can do that only when Entire EB2 category is current.
Example: There were around 10K EB1 and 20K EB2-ROW 485s pending 2 months ago. However EB2 IC got spillover inspite of pending applications. Only reason for that was that EB1 and EB2-ROW were CURRENT.
So yes, there is a chance that EB3 (ROW) may get spillover if EB2 does not have enough approved applications but the caveat for DOS/USCIS is they will have to make EB2 current (which i think will be a blessing in disguise for EB2 people.. although there will be a slight delay in getting their GCs.. but then good news is you can have EAD/AP and may not really care about the actual GC).
Makse sense?