This isn't a one size fits all type question, or one that somebody can really give good advice on without knowing the details of the situation.  Here's what I would ask myself:
- is your market very diverse (e.g. is it very unlikely the new competitors can capture a dominant share?)
- is your market large?
- do you believe you can supply something more than your competitors?<p>eventually, those questions should be used as input to the real question: can you still run your business successfully, or does getting beat to market by the competition prevent you from executing?