When a competitor acquires one’s customer(s), keep an eye on their usage. Common sense would dictate the newly acquired customer would quickly transition to a new service provider. If the acquired customer does not part ways, this would allow for some interesting marketing / pr material. Better yet, when the competitor renews the contract, make sure to take note of the renewal. One could use the renewal in aggressive marketing.
A lovely case study: SAP becomes NetSuite’s latest customer.