haber de necesitar

Hola Horace C.

Great question and perfect for a C1-level nuance!

The reason “habré de necesitar” is used instead of simply “necesitaré” is because it's expressing a formal, slightly old-fashioned or literary way of saying "I will need." This construction — "haber de + infinitivo" — often implies a sense of duty, inevitability, or reflection and it's especially common in narrative or elevated written styles.

So, while both of these are grammatically correct:

…the second form carries a slightly more refined or reflective tone, which fits well in storytelling or thoughtful narration — such as in the context of climbing a mountain, as in the Gorbea writing exercise.

Thanks again for pointing this out! Let me know if you'd like other examples of this structure.

Hasta pronto

Silvia