The framework I'm operating from includes the time-value component of the fund. If a fund has a target rate of return of 10% per annum, each additional year they wait for a liquidity event requires an additional 11% (1 / 0.9) in returns in order to hit their target.
So a valuation drop of 20% is comparable to ~2 years delay in liquidity. My strong suspicion is that the price volatility is small relative to the time volatility in these startups. There's a lot more knowledge around addressing the pricing volatility issues than the liquidity issues (an unexpected liquidity issue in the short-term markets is what caused both Bear Sterns and Lehman Bros to fail). In the end I believe that delayed liquidity events, in the market we are entering, are going to be strongly correlated with reduced IPO value.
To directly answer you question : the challenges of hedging for the time horizon of liquidity events will also include price volatility issues as well. So essentially if you're worrying about liquidity you still have to worry about price, where in saner times there are vehicles where you only have to worry about price. More hedges means more carry cost and less-profits. So what I meant by the "untenable" is that I don't expect the cost-value to be there in those circumstances.
Definitely possible that I'm wrong here, I just think the odds are against anyone dealing with those types of problems.