does a noun phrase followed by a prepositional phrase form another noun phrase?
The road to hell
‘The road’ and ‘hell’ form two separate noun phrases.
Does, ‘The road to hell’ constitute as a noun phrase in its own right? if not why?
What about something like,
The road of power
(i.e: using the preposition ‘of’ instead of ‘to’)
Yes, it does [form another noun phrase].
You can tell that easily by using it in a sentence with a main verb:
The road to hell is paved with good intentions.
The same can be done with any noun phrase.
The road of power is all in the mind.