It's completely in the same category as battery technology - interesting advancement, probably not going to actually get to production, even if it does it'll take years.
That said, it is still an interesting advancement of interest to the sort of people on HN. You could argue that this is one of the better forums for this sort of news because we mostly know what sort of pinch of salt to take with the promises.
It's not a breakthrough if sustainable energy output hasn't been realised. Initiating fusion is not the hard part.