I think to define your risk it is safer to buy puts on TNA about 6 months out from here. I am also expecting the volatility to pick up in this market which will cause this to start falling even if we just stay at this level or pull back slightly.
Why? If you believe TNA is going down you might consider buyuing TZA instead. It is a bit les risky since your risk in shorting TNA may be very ugly when it goes to 120 as I expect near the end of summer.