The hardfork has been planned for some time - its going to be phasing in the difficulty bomb which will increase the difficulty to the point where mining won't be sustainable anymore.
It is meant to transfer the PoW to PoS - so you will be able to hold ETH and "mine" it that way.
Theres alot up in the air right now, as the hardfork is being tested but it should be fine - according to the plan, at least