Well, that source I linked suggests a production rate of 63kg/h for a compressor of 177kW. If we assume every car is filled empty to full (the Mirai holds up to 5kg though an undisclosed amount is 'reserved'), then the station can do about 10-12 cars per hour without downtime. I assume that if you want to have something close to a petrol station flow rate you'd need about 60 cars per hour, so you're looking at 1MW grid connections for the compressors -alone-. That kind of makes the argument that superchargers will present grid connectivity issues a bit moot. That's also ~15kWh of embedded energy per fill-up on compressor power alone, which surely further impacts efficiency.
I do think hydrogen has a good future in trucking, trains, longer-distance buses and possibly even aircraft; big batteries for these applications are expensive, or for aircraft downright impractical. For cars though, hydrogen has never made much sense. There are only a few edge cases where it makes sense but the additional cost and infrastructure required just rule it out. Above anything else the fact that only Toyota is really following the technology says it more than anything else IMO.