Based on the assumption that the appeal here is the experience, not the actual legacy media, it seems like it would be trivial to implement a digital stream standard so that audio cassette players could record and play a digital stream for higher fidelity with an identical experience? Or would that not be possible on legacy media because of bitrate limitations?

I can easily imagine the DAC/ADC and amplifier tuning/stream processing being an optional step so that legacy compatibility would be perfect, and even dual head setups that could do on the fly conversion. But perhaps the data density of the tape just isn’t there? Though it seems like with the type of data stuffing tech we use it flash memory and hdd these days to quadruple up on bits per domain, that it should be possible.