> Is keto intended to be a long term diet?

According to the literature, I would definitely advise against it.

Good summary:

https://www.thepaleomom.com/adverse-reactions-to-ketogenic-d...

Higher all-cause mortality:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3555979/

Growth retardation:

https://www.sciencedirect.com/science/article/abs/pii/S00028...

https://www.sciencedirect.com/science/article/abs/pii/S00028...

https://www.sciencedirect.com/science/article/abs/pii/S02615...

https://pubmed.ncbi.nlm.nih.gov/12455855/

https://pubmed.ncbi.nlm.nih.gov/18676520/

Kidney Stones in children:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2852806/

https://pubmed.ncbi.nlm.nih.gov/11095028/

https://pubmed.ncbi.nlm.nih.gov/10893623/

https://journals.sagepub.com/doi/pdf/10.1177/088307380730192...

Bone mineral loss and bone health markers:

https://pubmed.ncbi.nlm.nih.gov/19064531/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6985427/

Benefits not sustained longterm. No better than high carb:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4674467/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4090010/

https://pubmed.ncbi.nlm.nih.gov/26413954/

“long-term consumption of an LC diet may increase the risk of development of gastrointestinal disorders.”

https://pubmed.ncbi.nlm.nih.gov/19224658/

Ketogenic diets inhibit mitochondrial biogenesis and induce cardiac fibrosis (in rats)

https://www.nature.com/articles/s41392-020-00411-4

Long-Term Ketogenic Diet Induces Metabolic Acidosis, Anemia, and Oxidative Stress (in rats)

https://www.hindawi.com/journals/jnme/2020/3642035/