So I am still none the wiser - which end are they talking about, and why do they need an ILS if they could use RNP instead?
ILS has broader reach of aircraft. Everything from a C150 through to a B747 can fly an ILS and will become operational the day they sign it out.
RNP however is only really limited to new generation jets and require much more pilot training and recurrency, (read money spent by the airlines) and may not be that popular with airline accountants.