I'm going to repost the same thing I put on the other article about this: I wonder what it says about me that my first reaction to seeing the figure containing the two artificial bases was 'They don't even have hydrogen bonds, what the hell is that shit?' I mean, look at it: If you have too many of these bases not hydrogen bonding, the DNA's going to fall apart.
IMO they don't seem to suggest that a future organism's DNA would be comprised by these specific base pairs. The primary achievement here was getting replication and retention of the artificial pairs, which is no small feat. They do have a relevant previous article: Structural Insights into DNA Replication without Hydrogen BondsIf you have too many of these bases not hydrogen bonding, the DNA's going to fall apart.