I dunno.
There is a fine line between theft of intellectual property and use of established technical knowledge in any industry.
State support for a developing competitor is nothing new and is hardly exclusive to China. Anybody ever looked at how much state support was given both Boeing and Airbus as well as any number of now defunct producers of airliners?
If the Chinese are really intent upon becoming competitors in the civil transport market and are therefore willing to devote the resources required to achieve that goal, then I think they will.
Ignore the next couple of decades of US and EU airliner sales and, as others have already noted above, look at China itself as a market along with all of the developing world countries who will be just as happy to accept Chinese airliners at a discount with friendly financing as they have been to accept Chinese infrastructure projects.
Let's not forget that my own country has pretty bad relations with much of what is called the Global South and to the extent that the BRICs exist as a block it's really only China that matters with India a distant second and Russia no more than a source of raw materials and oil. Not sure how Brazil really matters, although we don't enjoy cordial relations with them at the moment and Boeing has permanently lost the opportunity they had to acquire a competent developer of smaller airliners, just as they did with the C-Series. .