RE:Is it true?
Forget the effectively 80% part, but technically HVI should go to 0. But VIX never rose 100% in one day, and the ETF won't terminate according to the prospectus. VXX rose 80% over the last 30 days, SVXY (US version of HVI) dropped 51%. That is the danger of shorting HVU/UVXY over buying HVI, you could lose more than your initial investment.
Forgot the name of the guy shorting UVXY, but he/she may have to hold it longer than we'd have expected to get in the money, but there is a limit to how high spot VIX can go. It is now close to 40% of its all-time peak. The advantage with shorting is you can take advantage of the erosion while HVI can't (it has its own erosion, not quite as bad as UVXY).