Even if the chip never went obsolete, the scar tissue build up around implanted brain devices interferes with signal over time and they need to be replaced.
Also, each installation/replacement has a few percentage point chance of leading to a life threatening infection.
Unless both those issues are solved, irrespective of obsolescence this is only the sort of thing that makes sense for patients who feel that their life is effectively over without it and have low risk thresholds for treatment options.