First of all some corrections:

By constructing a device called an optical processor, however, researchers could access the never-before-used E- and S-bands.

It's called an amplifier not processor, the Aston University page has it correct. And at least the S-band has seen plenty of use in ordinary CWDM systems, just not amplified. We have at least 20 operational S-band links at 1470 and 1490 nm in our backbone right now. The E-band maybe less so, because the optical absorption peak of water in conventional fiber sits somewhere in the middle of it. You could use it with low water peak fiber, but for most people it hasn't been attractive trying to rent spans of only the correct type of fiber.

the E-band, which sits adjacent to the C-band in the electromagnetic spectrum

No, it does not, the S-band is between them. It goes O-band, E-band, S-band, C-band, L-band, for "original" and "extended" on the left side, and "conventional", flanked by "short" and "long" on the right side.

Now to the actual meat: This is a cool material science achievement. However in my professional opinion this is not going to matter much for conventional terrestrial data networks. We already have the option of adding more spectrum to current C-band deployments in our networks, by using filters and additional L-band amplifiers. But I am not aware of any network around ours (AS559) that actually did so. Because fundamentally the question is this:

Which is cheaper:

• renting a second pair of fiber in an existing cable, and deploying the usual C-band equipment on the second pair,
• keeping just one pair, and deploying filters and the more expensive, rarer L-band equipment, or
• keeping just one pair, and using the available C-band spectrum more efficiently with incremental upgrades to new optics?

Currently, for us, there is enough spectrum still open in the C-band. And our hardware supplier is only just starting to introduce some L-band equipment. I'm currently leaning towards renting another pair being cheaper if we ever get there, but that really depends on where the big buying volume of the market will move.

Now let's say people do end up extending to the L-band. Even then I'm not so sure that extending into the E- and S- bands as the next further step is going to be even equally attractive, for the simple reason that attenuation is much lower at the C-band and L-band wavelengths.

Maybe for subsea cables the economics shake out differently, but the way I understand their primary engineering constraint is getting enough power for amplifiers to the middle of the ocean, so maybe more amps, and higher attenuation, is not their favourite thing to develop towards either. This is hearsay though, I am not very familiar with their world.