[Distorted Humor]

The Federation I think could survive loosing 2-3 of its core worlds. (Earth, Vulcan, Andoria (if that is the right name) Teller prime, and some of the bigger newer members, like Betazed and Trill someworlds. ) However even a serious blow to Romulan or Klingon homeworlds would cause a major civil war, not only between the species uprising, but also from the remaining main species fraction. Also you would have species like the Breen raid in such cases.