Today, if a business has followed a model that focuses on flexible working there is very little that is business-critical in an office.
If the telephones are based on VOIP it is really simple to establish a new configuration that uses a number of mobile phones to substitute for the missing office.
The email, the applications and the data can still be accessed from the laptops as long as they have a connection to the Internet.
In most cases the only major difficulty would be the loss of the business printer, but basic printing facilities are cheap to purchase and easy to set up.