Hi all!
To recap and add some details:
http://www.wikidata.org/entity/Q12345 is the canonical URI for the concept
http://www.wikidata.org/wiki/Special:EntityData/Q12345 is the format- agnostic canonical URI of the *description* of the object (the data URI, for short).
http://www.wikidata.org/wiki/Q12345 is the URL of the HTML representation of the description of the concept (i.e. the wiki page)
http://www.wikidata.org/wiki/Special:EntityData/Q12345.json is the URL of the JSON representation of the description of the concept
http://www.wikidata.org/entity/Q12345.json works as a redirect to the above, but is discouraged, since it mixes the concept URI with a format suffix that is meaningful only for the description, not the concept.
Just to make things clear: This is the way it will be in future, too?
If I want to use Wikidata URIs instead of minting my own, I'll take http://www.wikidata.org/entity/Q12345 and Wikidata will keep that URI cool as in "cool URIs don't change"?
Thanks, Christian