We would like to upgrade our Sonar setup to 7.x but waiting for LTS release.
(i hope it is ok to "impersonate" the question for the 6.x LTS which g.ann was so nice to answer)
If such info would be made available on the interwebs somewhere we would not need to ask here.
cheers and thank you in advance!
As far I know there is no public schedule available. You can find the latest versions here. SonarQube 5.6 LTS was released in Jul 2016; SonarQube 6.7 LTS in Dec 2017 so it is likely that the 7.x LTS version will be released somewhere in the first half of 2019. The latest SonarQube news is posted here and you can also follow the feedback channels. On the Google forum (will be moved very soon) you can find messages about pre-releases for example. You can also have look at the cloud version; that will be updated first.
Update May 2019 In a blog SonarSource announced the end of support of MySQL, starting from SonarQube v7.9. So there will be one more minor version update before a LTS version is made or they skip v7.8. See the roadmap page regarding the new v7.9 LTS version.