It looks like your Norton 360 subscription has not been renewed. The contents of your disk are therefore encrypted. In order to obtain the decryption key, please submit your subscription payment within the next seven days. For your convenience, we accept Visa and Mastercard -- unlike some of our competitors that require payments only in BTC!

I could see an "encryption as a service" being added, where you can use it fine after you stop subscribing, but if you forget your info and want to recover/reset your password you need to pay ...

They'll harvest AV computer resources for DDOS attacks and give a portion of the proceeds from selling that service on the dark web to customers. It's clearly a win/win!

And to help even more customers the antivirus could spread between computers using the local network, or by emailing installers to all your contacts.

Or maybe they can automatically pay your ransom using the derpcoin wallet that you've been paying for via your power bill.