Even if it turns out to not have too many practical applications, just the ability to see quantum mechanics work with the human eye is breathtaking enough.
This ability would allow a quantum computer to do the mathematical heavy-lifting required for, say, cracking secret codes, while even the fastest and most advanced supercomputers plod along on the same problem.
In fact just this kind of photon-based quantum factoring has been accomplished before, but the ability to put the heart of the machine on a standard chip is promising for future applications of the idea.
The practical application here is that the ability to maintain entanglement for a long period of time is key to building real quantum information networks.