I would like to know any implications of doing the following, I cannot see any. This is a hypothetical scenario ..
If I had two physical sites, all on the same forest/domain and subnet. There is a DC in both, the DC in site A has all the FSMO roles, and both Site A and Site B DCs are GC servers. There is layer 2 connectivity between these sites, so its all the same broadcast domain and no routing.
What would happen if I broke the link between the sites, and siezed the FSMO roles to the DC in Site B. I'm presuming both sites would continue to operate as normal?
Apart from the obvious like not being able to address computers in the other site, I cannot see any problems with users logging on and authenticating? Should this work?