Take it a step further to the reversal of the aging process. Would we not become Homo sapiens sapiens immortalis?
"The man-machine stuff is mostly nonsense. I can see some limited use for specialized prosthetics. But nothing that anyone would consider a new species."
Cochlear implants are already being used to assist hearing. Artificial limbs, although crude, already exist. Artificial eyesight is on the horizon. What if we could have non-biological brain implants for augmented memory?
Replace just one neuron with a computer circuit. Is the person still human? Of course. Then replace 2, 100, 1,000,000 and more neurons with circuits. At what point does a person go from being human to being something else?
Take it even further. Replace all of a persons frail biological parts with non-biological parts? Is that person still "human"? What does it even mean to be "human"?
Each generation will decide for itself. We can't foresee the end result.