I found this interesting on the topic, somewhat realistic: https://indica.medium.com/how-space-is-not-going-to-save-us-82935a163276

That said, Hawking very much thought space was important to our survival. I'm of the opinion we're not as close to the dream as our VERY expensive experiments might make us think. We have the means and resources for small operations, but anything on a grand scale will require something more practical and sustainable and some technological leaps. It's entirely possible.