Need version hierarchy after Classic Board goes away

We have been using and depend on version hierarchy for as long as we've used Jira/Greenhopper/Agile (about 3 years now). It continues to work for now but I keep seeing references saying the Classic Board is going away. The only thing we still use on the Classic Board is defining the version hierarchy as we add new versions. I typically get a page timeout when I navigate to the Classic Board so I can only assume it's seldom used.

I'll explain our release cycle to give context. We release a major product version every 4 months (version 21 is active and 22 is under development). Each product version cycle contains about six 2 week feature sprints, several hardening sprints, release/upgrade for customer instances, and then about 4 to 7 patches to production instances until that major version gets replaced with next major version. We have a unique minor version number for each of these builds/releases that is a child to the major version number.

Without version hierarchy, a whole bunch of our filters that reference parent versions will stop working and become impractical. In other words, these queries would need to reference many versions instead of just the parent version. In addition, we often target issues first to a major release and subsequently to a child version (release build) as the more detail planning occurs. Without the version hierarchy, this practice will most likely become overly complex and no longer work. Yes, we do use Agile boards but mostly for high level enhancement/feature planning and not for all the defects and other gritty details.

Is the version hierarchy capability and behavior going to be migrated to core Jira? still part of Agile? Now that sprints and fixVersion have been separated it seems logical to move it to core Jira. I sure hope version hierarchy doesn't just disappear one day when Atlassian puts a new release out to AOD.

I've dug through the documentation (and Answers) and all I see is statements saying the Classic Board is going away. That's fine as long as the current version hierarchy behavior continues to be supported. Can I get a definitive answer as to the product plans related to this.