Porter's Five Forces: Threat of New Entrants for Airbids with intext citations. can explain Porter's Five Forces framework and how it can be applied to assess the threat of new entrants for a company like Allbirds explain me  five new entrants such as 1. Barriers to entry: 2. Economies of scale: 3. Product differentiation:   4. Access to distribution  channels: 5. Existing conflicts. strictly provide me a ApA references citation and intext citation for all paragraph and give me a brief explanation for each paragraph