Benefit of Sales/Stores are insignificant compared to proposed tax liability. All these can/will be outsourced the moment it becomes reality. How would EU calc

Benefit of Sales/Stores are insignificant compared to proposed tax liability. All these can/will be outsourced the moment it becomes reality. How would EU calculate profit share between US R&D and Ireland R&D ? Even if EU do tax R&D, exodus of talent will be just 2x salary increase away.