Of course Google, Microsoft et al were telling Ireland the other month that they couldnt raise their rates or they would leave. There is too much power here. Aligning tax rates globally will be necessary, like the EU did in Europe. On the other hand if GE is paying 3.6% then some loopholes need closing. Remove the ways to avoid tax and you can cut the basic rate. That was the plan for the abortive Reagan tax simplifi…
Playing the "exit" card is a desperation move, but its importance can be seen by the fact that it was actually revoked in every communist country. This was the purpose of the Berlin Wall, for example: to stop the brain drain of the skilled and talented, and keep them in a country with a 100% tax rate (the abolition of private property = 100% tax).
Therefore, it is somewhat arguable that governments are the "weak" ones here. Playing the exit card for MS or Google would cost them many millions and is a last resort.