Sure, with other changes. You would still have to:

* Select (or repair) “good” pairs that didn’t have poor echo, impedance, noise, etc. characteristics.

* Not compand the resulting PCM sample with mu/alaw companding.

* Provide an atomic bearer channel from the telephone switch to the ISP that was at least 112kbps.

* Develop a modem encoding scheme that could take advantage of the extra bandwidth.

At this point, you’ve reinvented a really crappy version of DSL that could be user-signaled to call different networks (i.e., phone numbers.)

The other option, the one that people selected, was to use the copper facilities but bypass the phone switch and its associated audio and in-band signaling shenanigans. That was/is xDSL.

No because you still have to modulate the signal to get it to/from a house, and modulation schemes are where you squeeze maximum bits per second into available analog bandwidth within the limits imposed by Claude Shannon.

The article didn't talk about modulation schemes and I wish it had.

https://en.wikipedia.org/wiki/Noisy-channel_coding_theorem going to https://en.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theore...

Bumping ADC to 16bit will remove some of quantization noise, but still leave you with inherent noise of the transmission medium and power limit (FCC/AT&T).