The situation with our ICD in the US has never been better, in spite of the damaging attempts of some advocates in recent years. ME is at its own distinct code matching the international classification, it's mutually exclusive with CFS, and the other historic ME terms (Iceland disease, Akureyri disease, and epidemic neuromyasthenia) are in the index and properly linked to ME. All that needs to be done is to adopt and use the proper nomenclature. This will require zero changes to the ICD, and assuming researchers start using the terms and criteria properly there should be no confusion between the medical literature and the ICD. Why would we want to further confuse things by creating yet another name and ICD code, that would not be linked in any way to ME or CFS in the ICD? Would SEID have an exclude clause for ME and CFS? If not, what would be the point of having a new code? If so, is the IOM really justified in creating a new disease out of thin air? One disease is not supposed to straddle multiple codes in the ICD. What chapter would you put SEID in the ICD? Does the SEID name and criteria really reflect the disease ME? Did the IOM really satisfactorily prove that ME and CFS are the same thing, when in fact they themselves state in the report that they are distinct? If we really must change the ICD, would it not make more sense to instead leave CFS at its code in the signs and symptom chapter and just rename it to SEID, leaving ME and its historic terms alone?
Regarding the original question, no, I don't think other countries will adopt SEID as they take their cue from the WHO ICD, not the US clinical modifications. As things stand right now, ME and CFS don't even exist in the upcoming ICD-11, so I think we have bigger problems on our hands.