If BTC core released an update to an 8MB blocksize , all of the Chinese Miners would update, and the rest would have to follow or get left behind.

Unlimited is higher than 8MB, and some of the Chinese miners don't want to go higher than 8mb, because they are concerned the Chinese internet infrastructure can't handle more than 8mb.

8MB could last for a few years before needing to worry about it again.
(When your house is on fire, you don't order a sprinkler system, you get as much water as possible and put out the damn fire.)
(BTC house has been burning for a few months now.)