If someone had a bout of severe dehydration that did not get treated medically in october 2102, is it too late now to reverse the consquences?

Can't say. : Not sure what consequences you refer to. Electrolyte disorders and kidney injury can be reversible, but your doctor would need blood tests to figure this out. Other consequences such as a stroke or heart attack may not be entirely reversible. Best if the patient be seen by a physician to answer your question completely. Best of luck.