There are still many other coins that aren't going to be delisted that have much lower trading volume than XEL. There are always coins that boom for a few weeks where the trading volume becomes one of the highest on Bittrex and then returns to "dormant" levels while traders wait for developments until the next cycle, that has happened for XEL a couple of times and it will again in the future. I don't expect Bittrex to delist XEL in the slightest, most coins that have a stable high daily volume have been around for a couple years or have huge community backing and there are many more tokens on the exchange that have a stable lower daily volume than a stable higher daily volume. Of course nothing is straight forward in crypto and there could be new regulations that change things for XEL, but for now I think it is safe.