In 楽しみにしています, does 楽しみ come from appending the み suffix to 楽しい, or does it come from the 連用形/V-stem/Masu-form of 楽しむ? I.e. Which of the following is it:
Appending the み suffix refers to generating nouns from い-adjectives such as:
Of note is that process above generates み-nouns from い-adjectives as opposed to being generated from verbs, and is capable of generating み-nouns from words that do not have a related む-ending verb (I.e. there is no おもしろむ→おもしろみ).
However, many of the above seem to have a corresponding verb which, of particular note, contains a -m- sound which could be related to the み suffix generation rule above:
It then seems that these may be possible processes (taking one of the ~める verbs as an example):
In this hypothesis, the verb is the origin. Some unknown mechanism (1)(Verb to Adj) generates a い adjective, and another mechanism (2)(Verb to Noun) generates a み-noun. Following this, a relationship between the adjective and the noun develops (3)(Adj to Noun). Then, this new mechanism (3) is extended to adjectives that do not have a corresponding verb containing a -m- sound, which is mechanism (4).
Comparing mechanism (2) to the 終止形 to 連用形 conjugation rule, we note that it is also of a similar type, that is to say that it is a process that is "Verb to Noun". E.g. 笑う→笑い.
In another hypothesis, I take the adjective to be the starting point. Where after (1') it gets a む to become 深む (Which may be an old verb form. See: Rare/Obsolete verb forms and How do 自他 triplets of related verbs work?) and then goes on to conjugate normally to 連用形 to get the み ending. As above, the association between the adjective and noun (3') is formed and is extended (4') to adjectives that do not go through (1'):
This gives me a suspicion that there might exist a verb-like む morpheme hidden in the history of the words that contemporarily do not have an explicit -m- sound in order for them to conjugate to a 連用形 containing み such that the processes A and B (right at the beginning of this question) are actually underlyingly the same process.
So restating the question, what is the path to take to get to 楽しみ? Is process A of the nature of (4) in the diagram?