For a USA style of Federation to happen in Cyprus, the island needs to adopt True Democracy. Without True Democracy, nothing will work in Cyprus. 1959 agreements have proven, that without True Democracy communities will want to do what ever they want. The north and south states cannot be GC state and TC state. No, they will need to be north and south states and ALL citizens living in those states will need to have ALL their Democratic rights respected, otherwise communal separation will occur on large scale as you have stated, which will be bad for Cyprus. Freedom of moment has to be a must, even if there is a short-term derogation on that in the beginning, but ultimately, the whole island needs to be free in every way.
USA has come a long way from its policy of the 50's, 60's and even the 70's. It is true, that individual states do have a lot of say what goes in their state, which is an argument I have made many times before, however, individual states cannot override Federal constitution. The states might try passing laws that might not be agreeable with the Federal Laws, and then it is up to the courts to sort it out. If the Federal government is in the right and the state is in the wrong and the state does dot back down, then the Federal government can and will hold back funds on any Federal projects in that state on such things as highways, bridges, ports and so on, not to mention political and economic pressure from other states also. It is not easy to get around the Federal laws.
kikapu there are many instances of states ignoring the federal government, including the reason for the american civil war. what would happen to cyprus if immigration restrictions were lifted by the tc state or derogations against gc were imposed and the tc state ignored the central government?