Is it possible for a foreigner to have his or her non PL-licence withdrawn?
Yep. If they catch you driving when over the points limit, then they'll seize the licence and prosecute you for driving while banned. The licence will then be returned to the home country, with a note saying that they've been banned from driving. Driving bans are (in theory) respected throughout the EU, EEA and CH - though there's no effective system as of yet to actually track these.