They were talking about a fall 2017 transplant but that did not happen. They are still saying it is imminent.
They have been worked on experiments with mice, dogs, and monkeys.
In November 2017, they transplanted a human head between two human cadavers.
There have been delays of months and years but they have funded surgical teams and have dedicated many years making progress to this goal. It seems clear that they believe that they can make this procedure successful, where the patient would survive for many months and possibly years and that the patient would be able to regain useful functions.
The procedure will likely cost in the range of $10-20 million and needs a medical team of about 80 surgeons and support staff.
The human cadaver trial must have cost several million dollars. The animal trials would also not have been cheap. The years of working toward this particular goal had a lot of opportunity cost for competent neurosurgeons.
As an observer of this, it is clear that Canavero is a true believer that this will be good and will benefit patients and humanity. It is clear that they have significant financial support. It is clear that there are people who would be willing to attempt the procedure. Therefore, it is a matter of time before it is attempted.
Ethicists and other doctors have been worried about the likely suffering and insanity of the patient. They worry that the person would only survive a few days in madness and agony.