While the days of ILS may be numbered it is still a far more reliable system that RNP at this point in time. I fly both regularly, including GNSS, RNP-AR and regular RNAV approaches. They all must be monitored very carefully especially during GP intercept. I have had many more problems with these GPS approaches than ILS. The future will definitely be RNP but not until there is a ground based element to allow CAT3 and filter out the built in errors of GPS. At the moment all it takes is the wrong QNH to be set in the FMS and the approach wont work as your crossing heights will be wrong. There are numerous examples of ATC passing the wrong setting! Think I will stick to ILS for a few more years.