There's an "easy" solution to "turf" wars: training programs need to get ACGME accreditation, strive for standardization of training, and restrict fellowship spots to tertiary care centers. NIR is and should be a multidisciplinary field that accepts radiologists, neurosurgeons, and neurologists. Physicians from all three backgrounds have contributed to the research and development of technology. And it's a perfect combination of principles from all three specialties.
As far as lifestyle, there's no way around it, but it should stay that way - akin to that of an interventional cardiologist. Once again, this falls back on education. Skills that should be learned by the Neurointerventionalist include things like neurocritical care and monitoring (all ICU procedures, intubations, EVD/Licox placement), vascular imaging/interpretation (including carotid ultrasound and TCDs), and significant knowledge of vascular anatomy/physiology. I think if training becomes standardized in this fashion, then within the next five or six generations, the model of care could be changed to allow for a more sustainable, busy, and consistent practice... i.e. angio (elective, emergent), ICU/floor, diagnostic reading (TCDs, carotids, CTA/MRA, angiograms, etc.). It would inevitably vary a bit depending on the background of the physician. This is just one person's opinion (I'm biased).
And yes, ridiculously cool field.