Like I can see them charge per completion, and charge too much so that it costs $100+/month to run for an average developer. Or crack down on unofficial "copilots" like https://github.com/zerolfx/copilot.el (although I really doubt more than 1% of completions go to these since they are niche tools; most people are using the official Copilot for VSCode)
It looks like there's a lot of competition though. I'll say right now, if Copilot gets worse and someone has a half-decent open-source alternative, I'll pay a substantial amount (possibly $50+/mo, which is a lot for a grad student), because AI code-completion is that useful