This is quite clear terminology in cryptoworld, although I can understand why people are a bit confused with the events that unfolded in August. A hard fork is any fork where new nodes produce blocks that old nodes do not accept (and vice versa). A soft fork is one where new nodes produce blocks that old nodes accept, but not the other way around (e.g. new nodes reject blocks made by old nodes). That's it.

So this _is_ a hard fork, albeit not a very contentious one. And it _will_ result in a chain split, with the minority chain probably having low activity/worth due to (1) lack of support (2) the ice age which will increase block times to slowly kill it (and that it itself has to be hard forked to stay alive).