Hello @Theklan, please have a look on https://meta.wikimedia.org/wiki/Requesting_wiki_configuration_changes.
Have you already reached a community consensus on-wiki ? Can you provide us a link to this ?

Hello @Framawiki. I think there is consesus on this. We made a votation and no one opposed it: https://eu.wikipedia.org/wiki/Wikipedia:Txokoa#PAGEBANNER

Change 368178 had a related patch set uploaded (by Urbanecm; owner: Urbanecm):
[operations/mediawiki-config@master] Enable WikidataPageBanner for euwiki

https://gerrit.wikimedia.org/r/368178

@Urbanecm do you need help deploying?

@Jdlrobson If it can be deployed normally during a SWAT window then not :).

I've scheduled for swat at 11am today (in 20 mins time) should be up within 80 minutes from now!

That's great. If you'll need me during the window, ping me, I'm sitting in -operations.

Change 368178 merged by jenkins-bot:
[operations/mediawiki-config@master] Enable WikidataPageBanner for euwiki

https://gerrit.wikimedia.org/r/368178

Mentioned in SAL (#wikimedia-operations) [2017-07-27T18:22:28Z] <catrope@tin> Synchronized wmf-config/InitialiseSettings.php: Enable WikidataPageBanner on euwiki (T171763) (duration: 00m 46s)

Yes @Jdlrobson, it works on user pages and sandboxes, but it doesn't seem to work on articles or wikiprojects!

hmm.. that's strange.
$wgWPBNamespaces = true so this should work on all namespaces.

It works for me (main namespace.. but haven't hit save):

Maybe it needed some time. I saved in "Test" and it didn't work, I changed the "New Wikitest mode" in Beta off and then it worked. Maybe there's a bug there!

Done! https://phabricator.wikimedia.org/T171888