I understand that the US is likely vulnerable to cyber attack, but is a widespread attack by China likely in the immediate future?

I mean, let's say China does disable infrastructure, banking, etc in a coordinated and widespread attack. But then what? An attack on that scale is an act of war, and I doubt China would be willing to follow up with military action at this time.

Perhaps this is more of a preventive MAD type strategy? Essentially a warning to the US to not mess with China, or else these are the consequences.