Competitive Forces Analysis for Market Entry

In the context of a hypothetical industry analyzing competitive forces, a company, XYZ Corp, is considering entering a market characterized by significant barriers to entry due to high capital costs, stringent regulatory requirements, and an established customer base loyal to current providers. Additionally, there exists a high degree of product differentiation among competitors, and the threat of substitutes is moderate. Given these conditions, which competitive force is most likely to pose the greatest challenge to XYZ Corp's entry into this market?