Scenario 1
You have lost funding for some of your work, but this work is not a major contributor to funding your overhead costs, so your main concern is the loss of the activity rather than the threat to the overall sustainability of your organisation.
Consider:
Scenario 2
You have lost funding for some of your work, and this work is a major contributor to funding your overhead costs, so there is a real threat to the sustainability of your organisation.
Consider the issues in Scenario 1 plus:
Scenario 3
You have lost most or all of your funding, so it is likely that you will have to close down.
Consider the issues in Scenario 1 plus: