Hey Balázs,
I haven’t got anything more precise than last month, and to your question:
Pretty unlikely, given that 6.7.x LTS dates late 2017, and the current cycle is approx. every 1.5 years.
A question for you though: anything specific reason for caring so much about 7.x LTS ?
Lifecycle and feature delivery of SonarQube is evolving as it grows up. You can’t really compare 5.x with 6.x lifecycle. We’re firm believers in continuous integration and continuous deployment (we have to! think about SonarCloud 
), so you should feel completely at ease with using the very latest version of SonarQube.