Well, a 10:1 improvement in the cost of the infrastructure for "just the storage" OBVIOUSLY leaves out the cost of conversion from heat to electricity (the article even said so, more or less). This latter part, 2nd law of thermodynamics notwithstanding, has been THE problem all along in making electrons move through wires so that we can watch TV and read by electric light... and in some cases, heat various rooms in the house that aren't practical to heat any other way.
And if you're going to go THAT far, we might as well use URANIUM to produce the heat in the FIRST place. Until, of course, hydrogen fusion reactors become practical.
It's obvious that politics of the day are driving all of this.
/me plays "Baby it's cold outside" - not simply because it IS getting colder, and will continue to get colder, on average, in the Northern hemisphere, until ~2040 due to the ~70 year temperature cycle, but MOSTLY because I heard some people whining about that song recently and so I'm having fun with it.
To the scientists who suggested 'hot rock' storage: Nice try. How about 'Nuclear' instead? Nuclear doesn't generate CO2, the thing you fear the most. But wait, it's not in line with the POLITICS, now is it? Heh, yeah, pointing out the obvious again. I think I prefer FREEDOM.