If an interviewer makes a case like this, you should try to better understand the context. If no additional context is provided, I would try to solve the case by making assumptions on key variables characteristing market entrance and discuss different scenarios.

For instance, consider these 2 variables:

• Client market share
• Type of market entrants

Depending wheter:

• The client is market leader vs minor player in the market
• New entrants are large corporations growing by adjacencies vs new emerging startups testing a new business model with strong traction

By mixing these factors, you could already build 4 scenarios and provide a structured answer to the interviewer.