They do have the same supply chain challenges. Look at the iX3 steering wheel. They're going to be stuck with that until their next one has finished development.
If the NK fails (which hopefully it won't), then BMW would have similar issues with pivoting, because their entire manufacturing setup and supply chain was geared to make NK cars.
We're talking about plastic molding, part supplies, metal machining/bonding/welding, etc which are geared to be in use for several years.
This is all fundamental to product lifecycle management.
Chinese manufacturers are more flexible, because they are often part of companies that make more than just cars. They have almost complete vertical integration that other car manufacturers do not. That and heavy government subsidy offsetting losses from mistakes.