Not that far from reality
As the headline suggests the method used here is pretty exotic, it's true.
But if the application is Data Centre Interconnect (DCI) then there are far easier ways to do this.
The DCI market generally needs reach of less than 150km, because it involves interconnecting a distributed "metro" data centre (one where the operator has leased buildings in different parts of a metro area and needs to interconnect them as though they were one big building). The big ICPs like Google, Facebook, Microsoft, Apple, Amazon and Softlayer do this all the time. And they have a limitless demand for capacity...seriously...check out some of their keynote presentations.
There's commercially shipping technology that can put over 27Tb/s on existing fibre (not this multi-core stuff, which is still experimental). This commercial technology uses the C-Band. By simply extending it to the L-Band you can double the capacity to a little more than these boffins achieved. And L-Band is easy-peasy. We've known how to do it for almost 20 years, but people have tended to stick to C-Band because it's the sweet spot. Next gen technology could increase the Baud rate, or the modulaiton order, and easily double or maybe quadruple the capacity. Check out this blog wot I wrote on two post deadline ECOC papers that use actual fibre that exists today. One talks about higher Baud rates, and the other 1024QAM modulation with a technique called Constellation Shaping.
But if people really do need the capacity L-Band is there. And so is the O-Band, E-Band and S-Band (in most modern fibre...older fiber may have some water peaks in their attenuation chart).
Since the reach is so short we don't need in-line amplification on these links, and so all of these wavelengths are potentially "open for business" in the DCI market. And the key point is that you don't need exotic new fibre. This is good old SMF, LEAF, or whatever you've got in the ground today. And generaslly speaking there's shedloads of fibre around is you need it.
So I'm pretty scepitcal of the multi-core and photonic bandgap fibre experiments. Maybe one day...but there's so much capacity still to come in existing fibre (as long as you don't need to go a long way), we're OK thanks.
By the way...we don't make fibre, so I've no axe to grind there. If people do get this multi-core fibre to work (and can make enough of it, and can build an entire connector and splicing ecosystem to support it, and are willing to pay to lay it in the ground) then I'm sure DWDM vendors will happily use it.