Presumably they'll choose the companies who can/do service them best. I work for a contract manufacturing company and the same thing holds true for us as a $6b corporation with a presence in 25 countries. Customers pick the partner who provides the right mix of cost, quality, communications, timeliness, location and alignment. Depending on the customer's own business goals and performance, the list of eligible partners ebbs & flows over time. Generally speaking, though, the cream always rises to the top.