Hi Robert, welcome on board!
I know nothing about Control4, but you can read about other people’s experience here:
Essentially, because Control4 is a closed system, nothing else can be integrated with it (bear in mind I know nothing about Control4 so hopefully I’m mistaken and some things can be re-used), so if you’d like to “migrate” away, essentially you’ll have to replace everything, rip out control4 and replace them with something equivalent.
I think you’ve come to the right place for the most ideal replacement, although I’m biased of course because I love openHAB. I’m just an openhab user, no different to you, and I certainly don’t gain anything whether you use openhab or not.
Once you’re ok with replacing everything, then we can start with you listing off what you currently have and perhaps what you would like to have. We can then probably make suggestions as to how to proceed forward.
Are you interested in tinkering with / implementing this all yourself, or are you looking for a “turn-key” system where someone comes in and do it for you, perhaps similar to how Control4 worked in the past?
EDIT: another post with some information on how to use / integrate Control4’s multi-room audio system with openhab: Multi-room audio controllers from Control4 supported?
But if I were you, I’d remove any trace of control4 from my house and replace it with something I can easily replace myself without having to have someone else come and do it for me.