Are we supposed to be opening threads about this new free Cakewalk in this Sonar thread? Shouldn't there be a dedicated Cakewalk category?

This is the right place for now.
There is a new forum in the works but has yet to be rolled out.

OK. I wanted to be sure I wasn't posting questions in a Sonar Forum when I do not use Sonar anymore. Thanks.

Given that the new Cakewalk is essentially an advanced version of SONAR Platinum, 99% of the questions and answers posted here will continue to be applicable to both for some time. Hopefully, the old SONAR threads will be archived and made available from the new forum when it's implemented. So yup, this is the place for now.