That might work, although I think there are two limitations:
1) Hearing aids have a 10ms latency budget. So no matter how much processing they can do, they're limited by how many samples they can look ahead and that limits the design of the filters. The brain can presumably look ahead further to separate sound streams so I think it's pretty impressive that ideal binary masking works.
2) Hearing aids have a power budget. The ones I've looked at achieve low power by running a FIR filter in hardware to shape the sound while a DSP classifies the sound and adjust the filter taps. The DSP doesn't have to run at the same rate as the filter. That seems well matched to the binary filter approach. Likewise features extraction might not run at the same rate as the DNN.