Those of us who already have Sonar Platinum installed, are we good to go? Or do we need to download something else and overwrite the old program? Or does the new thing automatically replace the old one?
Thank you
WSS

It doesn't overwrite the old version, it's like updating from X3 to Platinum was. Except it's more like just installing another version of Splat along side what you already have. It uses a different app to install. DO NOT un install SPlat. 
 
 I've un installed it already as I could not see using it at this time. I'm happy it exists but it need to grow a little yet. 

So many info in those sticky threads if you have any question. Just take some time to read them. In case you need summarize, then :
 
If you run x64 machine, with internet connection, and don't mind signing up for BandLab (free) account, then yes you are highly encouraged to download Cakewalk by BandLab, since this is the one which will continue supported. The "Sonar Platinum" is no longer supported.
 
The "new" Cakewalk by BandLab wiill NOT overwrite your current Sonar Platinum. You will have privilege to use them side by side. Your any previous Sonar installed will NOT be overwritten. You should NOT uninstall Sonar Platinum, unless you never need it's bundled 3rd party contents, plugins, instruments etc.
 
Hope it helps.

That helps indeed. Thank you.
WSS