I agree with your post while adding only that major public utility infrastructure suppliers already have Autobidder-like products. AFAIK none thus far have integrated large supply (e.g. utility solar and/or large wind, with small household-level suppliers as Tesla does with VPP, while providing effectively instantaneous response times. Even if none do that today, the EU/UK demands today from wind, in particular argue for seamless integration of every supply source and demand destination within a single grid. Because this is both obvious and crucial Tesla VPP mimics are about to be ubiquitous.
For context, ask
@NicoV, whose own house and cars benefit from this capability in Belgium today. I do not know the software provider there, but perhaps he does.
Just as nearly all of us are sure that Tesla has giant opportunities in this sphere, so too do a plethora of other suppliers.