Why doesn't 「になるではあろう」 have a の in it?


In

> 勇者よ、王都から何百パシリもある長い旅路 **になるではあろう** が、古代都市カッタイナ・カに行って伝説の秘宝ソンナ・アホナを手に入れるのだ

Why is there not a nominalizing の after なる and before the particle で? Doesn't
the で in では need a noun as an argument?




精選版日本国語大辞典 has [the following on
である](https://kotobank.jp/word/%E3%81%A7%E3%81%82%E3%82%8B-332613):

> **活用語に直接する** のは、現代語としては「であろう」「ではないか」およびその丁寧体の場合に限られる。

So, it can drop の because it uses であろう.

Compare in case of である:

  * 長い旅路になるである is wrong
  * 長い旅路になる **の** である is fine (as you thought)

The phrase in question can be understood as the above であろう + は inserted for
kind of emphasis (or 取り立て).




In this case ではあろう is being added to the plain form of the verb just as だろう or
でしょう would to form a 'tentative': compare 呼ぶだろう 'I think [someone] calls, will
call'; 大きいだろう 'it must/would be big (I think)'.

Hence なるではあろう is like なるだろう, plus it has focus on the predicate via は, which
adds an emphasis, as in English 'it WILL be a long journey BUT...'

Addendum

If you want to add polite stylization to a verb, you can just add です, so 呼ぶです
is equivalent to 呼びます. I don't know how frequent this usage is now, but
certainly in the negative, 呼ばないです, and the past tense of adjectives, 楽しかったです,
it is common. Adding のだ・のです to a sentence is completely different. The basic
meaning is 'the act of S, the fact that S, the one which S', but it adds other
connotations or nuances, like indirectness or politeness or reservation (for
the latter, compare 行きたいんですが, 'I would like to go but...[is that OK]?').

