Actually probably not such a big deal, except for the Navy, the geothermal plant, and the other very few people in the immediate area. Any future eruption is likely to produce features similar to those already there: cinder cones, and lava flows extending a few kilometers. If a future eruption includes more silicic lava, a plume of volcanic ash may extend a few tens of kilometers downwind. For more info on the geology, history, and hazards at Coso, see the USGS at: Coso Vocanic Field.

Regarding the relationship between Coso and the recent big earthquake, it is not that unusual for a big quake to trigger small aftershocks at a nearby dormant volcano. This is a very seismicly active area, and no doubt Coso has been jostled numerous times in the 40,000 years since its last well dated eruption. According to the USGS Coso hazards page there is no indication that an eruption is imminent, at the present time.

There is a nice very detailed discussion on Facebook posted at https://www.facebook.com/andy.frassetto/posts/10108643920765392?hc_location=ufi, by someone who actually knows something about Coso and it's geologic context.