It seems like the most successful SaaS companies eventually expand beyond their initial product category to become a platform with a wide range of services and

It seems like the most successful SaaS companies eventually expand beyond their initial product category to become a platform with a wide range of services and a whole ecosystem around them. Some go really wide, like Salesforce, while others seem to try to keep some coherence around the core product (at least for now), e.g. Zendesk and Intercom. It seems Twillio wants to go quite wide too.