November 16th, 2023 update: It finally happened:
No longer available as a perpetual licence: only via subscription Another key change in ZBrush 2024 is that it is only available via subscription. [...] Maxon has announced that ZBrush 2024 will not be available as a perpetual licence, making the new features subscription-only.
Not just "the new features". Now, subscription is the only option for those late to the party:

No comment. The original blog post will stay here for posterity:
As one of millions of ZBrush perpetual license holders, today I received this gem of an offer from Maxon:

With the following description:
ZBrush has always stood for innovation and artistic empowerment. That is a philosophy that is shared by the Maxon creative community. We believe in empowering artists any way we can to help expand your capabilities and offer more to your clients. We are confident that having complete access to all Maxon tools, services and training will help you achieve your goals.
Just another bunch of corporate mumbo-jumbo with a poorly concealed attempt at selling a subscription to a perpetual license holder. Classic.
"...We are confident that having complete access to all Maxon tools, services and training will help you achieve your goals."
MAXON is about to acquire Pixologic!

If you were hesitant about purchasing that perpetual ZBrush license, YOU HAVE TO DO IT ASAP before they make it subscription-only, just like they did with Redshift Renderer!

It just keeps getting better, doesn't it?