At first sorry for my english. But I think for the QR in wikipedia could be the possibility to use for each article instead of the Lemma an unique ID. In the german wikipedia it’s possible to use this so can e.g. instead of URLhttp://de.wikipedia.org/wiki/Wien the URL with ID
http://de.wikipedia.org/w/index.php?curid=5632 – In the case of move of the article e.g. to Vienna (Austria) the ID would be same later too.
The second cause to use the ID is the small URL with the small number, at this time till 6 digits) instead of a long lemma of atricle – so the QR-code will be verry smaller than with lemma.
One database in Austria works in the meantime with these ID (you see it in Noe Landesmuseum with link to wikipedia) unfortanetely in german
this would be only an idea to this matter