Is it the end of the line for niacin?

No, but a new study presented at ACC raises concerns.  Before jumping to conclusions about niacin note the following:

The results do not permit a distinction between niacin and the antiflushing agent laropiprant in attribution of the negative outcomes.

The patients were studied without regard to LDL particle density, ignoring previous findings that niacin has a powerful niche in patients with low LDL particle density (LDL pattern B).

In the trial, niacin was combined with a statin with a higher toxicity profile.

In the Coronary Drug Project, an example of comparative effectiveness research done decades before the term was co-opted for political ends, niacin was the first lipid modifying agent found to favorably impact significant clinical outcomes.