I think market share most likely would have to come from outside of US.
Regarding the other markets - they might be blocked in EU due to Shire's orphan exclusivity. Pfizer/PLX are challenging Vpriv's orphan market protection based on Sanofi/Genzyme’s manufacturing situation and Shire's capacity constrain but if Cerezyme's supply improves and Shire gets clearance for its Lexington facility and triple current capacity, then PLX's case might not be strong enough.