Report Builder

Not only are there no plans to upgrade it, but it was marked as deprecated in CF2016, which means not that it is removed but it may be removed in a future release, and it is no longer being updated (it hasn't been for a while, as you may know.) And to be  clear, I've not seen any plans to offer anything like this going forward.

As for alternatives, there have been various java-based reporting solutions. Folks have traditionally looked into jasper reports, when I've heard the discussion (never pursued any myself). But note that any alternative would not integrate with CFREPORT, in the way the CF Report Builder would, so one would need to change their code as well as use/learn a new report builder.

Some good news is that while it may seem that the "change of code" would mean calling java objects (for the report builder's output) from within CFML (and that's really not too hard to do), there may well be some CF library someone's created that already provides that integration in the form of a CFC whose methods you'd call (again, I don't know of any). Or it may be that such a Java report building tool uses JSON or REST or some other means to communicate with it.

And such a Java-based solution may be a jar one implements within CF, or it may be a separate process one installs and runs outside of CF. And for that matter, there may be a reporting solution that is NOT Java-based which again one could call from within via rest of other means.

So while I can't offer you THE alternative, I am saying that there SHOULD BE alternatives you COULD use. If you dig in, let us know what you find, or perhaps others will chime in.