That will depend on the relative bargaining power of the two sides, and neither side has a natural right to any bargaining power advantage. Each side's bargaining power depends on the attractiveness of its alternatives. However, and this is the central point, notwithstanding Section 13 of the National Labor Relations Act, like-minded workers who simultaneously withhold their labor services have no legitimate right to interfere in any way with the right of the struck employer to engage in voluntary exchanges with customers, suppliers, and other workers. Workers who are willing to work for a strike employer who wishes to hire them have a legitimate right to do so. Moreover, they may agree to accept the very terms of employment that the strikers consider to be unacceptable.
Replacement workers have the same job-related natural rights as striking workers.
Unionists resort to name-calling to imply that replacement workers don't have the same voluntary exchange rights as other workers. But scabs are human, and as Thomas Jefferson would put it, they are endowed by their Creator with the same unalienable rights as any other human. Notwithstanding the tenets of legal positivism, not even Congress can justly take away unalienable rights. The National Labor Relations Act became law in 1935. The law guaranteed a right to strike and to use picket lines to try to prevent the struck firm from operating.