There are many such allotropes of well-known substances. For instance, solid water has over a dozen allotropes (including ice-IX, or "ice-nine", which will not turn you into a human popsicle). Most of the interesting allotropes of ice only form under pressures of >100 MPa, so they are never seen under terrestrial conditions. The same applies to most other allotropes, with a few notable exceptions in metals and metalloids (like tin and sulphur).

It's unclear to me what the author of the article had in mind when they suggested the "potential" that "black nitrogen might have for electronics". Unless the author is imagining electronics which must be placed under immense pressure and heated to thousands of degrees to remain stable?

In this case, we have something that may be similar to graphene, but can only exist at 4000°C and 1.4 million atmospheres. Graphene is interesting for electronics, so they suggest black nitrogen might be useful for electronics too. But of course graphene has the slight advantage that it's relatively easy to produce and doesn't dissolve at temperatures lower than the surface of a star.