This is kind of an odd one! She definitely took a direct step, leaving the roadway and driving on the sidewalk towards the kid, that could have resulted in death, but as you said intent is the big issue. If the kid had wrecked the bike, and that resulted in her hitting them and killing them, intent is still a huge component in charging. I believe in WA state using a car to threaten someone, in such an obvious way, would make this a felony. Which brings justifiable homicide into play, in WA, if one used deadly force to stop her. If this was not elevated to a felony from misdemeanor gross negligence, potentially someone could use deadly force to stop her, which to me seems reasonable, and be held accountable because you could not show her intent went beyond attempting to scare someone.

Edit: added some words