I wouldn't say "server under your desk", necessarily; more of an "Linux getting big" era of IT.

If you want to host the model on the server under your desk, you can. If you want to build a data center on-prem to host it, you can. If you want to pay a cloud provider to host it at their data center until you figure out how to scale it without their help, you can. It's like when people were first building commercial services to support Linux-based OSes, and people were also still hacking on it on local machines.

APIs may still have their place - maybe you just want to throw your devs a known quantity with all of the management built in - but it's not going to make Sam Altman a trillionaire, which is something anyone outside of the SV echo chamber could have figured out as soon as the first real competition to OpenAI emerged.