There is a lot of room before that. Rather that the Guard would intervene illegal searches etc, and the inevitable tense ICE - National Guard interaction would change the dynamic, temper ICE's behavior. Moreover, the expected outcome would actually be Trump trying to nationalize that guard, then a constitutional crisis/emergency supreme Court intervention. The most power move that Democrats could make right now is the Republican one: state's rights/ sovereignty

I think your assessment is accurate and realistic.

But ICE is behaving pretty sloppy. I'm not sure it could get to that point without (just due to risk multiplied by sheer number of interactions) ICE accidentally escalating something via sloppiness, crossing something that they don't value but is a hard line to their local PD security detail, refusing to stop and getting smoked that way, either by their own security or by a passer by while their security shrugs.

A fed might not care about literally doing a George Floyd, but your security force might just walk off rather than be party to that.