Uncertainty has caused investors to "bank" their BTC/ZEC/ETC/ETC, and any other currency that has a USDT tag.
An increase in USDTBTC volume and volume of any other USDT tagged currency will indicate that a subset of investors are willing to convert their "banked" money back to digital currency.
It will also indicate that 2.5billion dollars (USDT market cap) is starting to enter the market. This number we see as negligible, the physiological move among investors is more significant.
Combined with the usual BTC indicators this is a useful addition.