Honestly speaking 4000 hours is not much. People will hardly loose just 100-150 Dollars. But the 1000 Subscribers Threshold is like asking for too much. It took me to 2 and a half years on my main channel to get there. By the time i hit thousand subscribers i had already earned 1000$ mostly because of the content i made. These thousand dollars helped me grow. I bought camera, lighting equipment, yeti microphone and more with that money.
The channels who gain subscribers quickly before hitting 4000 watch time will not loose much. But those who upload with out good equipment and gain less subscribers will get affected now.

I will be loosing demonetization on my second channel by 20 th Feb. I don't have thousands of subscribers there.