Welcome back! You don’t need to do anything if you can do what you want to in 8.5pro? A lot has changed since 8.5 but if you need an upgrade is up to you? For one ‘big’ thing …32bit plugins are not supported anymore. So if you have precious gems that are only available in 32 bit be prepared for that!
I had kind of a phase probably similar to yours some years back where I totally abandoned music creation/production. But since 2013 or so I’m fully up and running again. 
I can tell you it really helps to read in and follow the forums (Steinberg, KVR, Gearslutz, etc) and maybe other useful stuff. It will take you a while to get back into the ‘flow’ but you’ll get there if you really want to?