What a incredible e-mail from Atlassian, cloud first. Not everyone wants to use the cloud. I worked with Confluence and Jira over ten years now. Time for alternative Wikis. I am a little bit sad about the cloud first strategy. Confluence and Jira are pretty cool tools.
Time for alternative Wiki´s

https://wiki.js.org/

This Wiki very close to Confluence. But one feature is missing

https://wiki.js.org/feedback/p/multi-sites

Multi Sites

BlueSpice based on MediaWiki but it have a lot more features and a good Editor.

bluespice.com

Multi Sites only available in the enterprise version.

Also look at tiki.org but is more than a wiki

For Jira alternative

I found

http://www.tuleap.org or https://www.openproject.org