I'd want to use a "Wikibase entity" datatype to templatedatas. "Page" dataype is not enough for Qids or Pids, so we have to choose something else, like free text who is not appropriate either

There is several ways to enter an entity value ; the Mediawiki way as "Namespace:Pagename", the web URI as in "https://www.wikidata.org/entity/Q11344" or the web URI of the wikipage of the entity "https://www.wikidata.org/wiki/Q11344" (more easily copy/pasting possible) or the same in Mediawiki space address [[:d:P:31]].

Some of my templates like https://www.wikidata.org/wiki/Template:Q' can use all of them.