What do you mean by "stop tolerating"? Declare war?

I suspect at the time one or the other puts their foot in the sand, that it will escalate to a conventional war.

Let us hope that day never ever happens. It would be awful for both sides no matter the "winner". As I learned from spending a year as a UAV Pilot in Iraq from 2003-2004, in war, as soon as a single person on either side is injured, both sides permanently lose. There is no real "winner". Just one side that loses less.

Unless you can make the case that risking commercial relations with the current largest economy in the world over these attacks makes sense... I would say never.

The US has regularly attacked non-US companies and people, mostly by spying on them.

I agree. It would be nice to see the president or some government official at least publicly acknowledge that a US-based company is currently under attack by the Chinese government.

Things will become worse before they become better.