If I use Home Assistant for control and block the Hue hub from the internet, will things keep functioning as they are today?

I like how my stuff works and don’t want them to mess me up.

To be safe long-term I would probably suggest to throw away the Hue hub entirely and get a Zigbee USB dongle for your Home Assistant server. Personally I’ve had no issues with the ConBee II. Home Assistant also released their own dongle earlier this year, called SkyConnect, which I’ve heard is pretty good as well.

(This is assuming that all Hue devices are based on ZigBee, which I believe they all are, based on this useful database.)