Apple Music question

Hey, guys. Defector from Android here, now back in the iOS camp and thinking about getting an Apple Music subscription. I just got off live chat with Apple and they didn't answer my question, so help me Obi Wan Reddit, you're my only hope.

I have a current mishmash iTunes library consisting of traditionally purchased iTunes tracks, some ripped CD's, and mp3's that were purchased and downloaded from Google Play Music and then added into iTunes.

Some of the CD's in particular are not, and never have been, in the iTunes or AM catalogue.

If I subscribe to Apple Music what happens to those those CD and mp3 tracks, especially the rare ones that aren't in AM? Are they gone forever if they can't be matched?

I know I can keep them in my current device, but I'm especially thinking about if I buy a new device or have to factory reset my current one. What happens to those tracks then?

Thanks everyone, sorry for droning on but it's driving me crazy. iTunes and IOS so far has been one problem after another and it's only been a week.