Tesla will come to the utility and say we can offer you 3000 MW of demand response in any granularity you want for $x/hr.

$x is usually not very big since the modus operandi for the bulk electric system in North America has been everyone can use as much power as they want whenever they want, so we have had lots of supply.

But a couple of times per year $x could be thousands of dollars per MW per hour, for a few hours. So not worth the effort really.

Maybe Tesla will offer the demand response more geographically so distribution utilities can also use it for peak shaving on their substations. But that is pretty brave area to be operating in for a utility, depending on Tesla to avoid overloading transformers or risk a localized black out.

There would have to be a serious penalty for bidding in the demand response but then not performing as well.

I agree it does seem far fetched at this time.

Edit: price signals to consumers is probably a better mechanism