Fine they needed the Termination Clause there to prevent the ETN(F) value to go below zero as its notional value could do if the market dropped too much. But couldn't they just set a limit to what its notional value to be say 1 if the market drops too much to give it a chance to reverse split? I mean reducing the leverage doesn't really eliminate the possibility of the "meltdown"; it could still happen.
It would have been more ethical, to create a new product with the changed leverage! And if they really wanted to terminate the -1X version, phase it out in one or two years! This would allow an orderly transition. This horrible handling will likely result in loss of confidence in ProShares!
Extremely uncool to change this on an existing product: 1. It screws over everyone who is using this product for some kind of utilitarian purpose - forcing them to rebalance and/or outright change products. 2. It reprices all existing options, option strategies, etc. 3. It screws over any kind of charting based on it. As @stepandfetchit said, a new product would have been the proper approach.