RNP vs Ground based navaids :
It is the future of navigation.
My turf now : You are probably right depending on your definition of " future",
long term , probably , next 20-30 years ? probably not.
We all thought in the 80'and early 90's that HF, NDBs , VORs and ILS would have disappeared by 2000. But here we go, HF transmitters and NDBs ( mainly IAFs), ILS are still manufactured new today as we speak..
Main reason is redundancy and ownership . GPS is still a military system owned by the US Military who can switch it off or degrade its accuracy when they like,
Many States do not like this.
So as long as Gallileo or whatever new independent system comes up ( but at a cost of course) , ground navaids are here to stay in some parts of the world at least .
mark my words,