Basically bitcoin trajectory burning fuel to do useless hard math just so that you can't compete. I see same thing happening with AI chat which will pitch AI against AI until one party can't keep up all while burning fuel doing useless math.
I think in the short term its cheaper for these scam call centres to use "local" English speakers (in practice many of the employees are fresh-faced out-of-towners looking for their first job) than it is to dev and maintain an entire GPT pipeline. It will require a level of completely different organisation and sophistication than what is currently in place. Right now outside of running the dialler and internal off-the-shelf packages to manage their workforce these orgs are not particularly tech literate as evidenced by the YouTube channels that expose them.
For "legitimate" (the kind that's not a scam, just annoying) they are regulated that it wouldn't be legal in many jurisdictions. (at least in B2C context -- maybe it a bit lax in B2B, considering Google's already using some form of bot to confirm business hours for Google Maps listing.)
Scammers in other hand already employ illegal robocalling tactic, and I can see some may opt to use systems like that if the price is right.