Regarding the original question.
I go, would mean I leave. It's the only sensible interpretation. But native speakers don't usually say things like I go, in the simple present. Usually, they would say I am going, or I am leaving. Appropriate 'predication' depends on the intended meaning. I go to school, in the present simple is a statement about the subject's routine or habit. It is not sensibly interpreted any other way. If you want to use go to mean leave, then it would be better to say I am going to school, now, or better yet, I am leaving for school.
So this is an example where the grammar rules actually interfere with language acquisition. Syntax is about the common patterns in use to establish meaning. Just because a rule would allow you to construct a sentence, doesn't mean it represents the syntax of English. Language is about patterns not rules, the rules may follow patterns, but the patterns do not follow the rules.
Regarding the so called 'incomplete predication' question, it's seems that a verb's completeness depends on its intended meaning, and in the examples given the meaning is different.
- God is. This means God exists. The meaning that the verb be takes here is to say the subject exists, an intransitive state verb. Normally, people would use the verb exist in such a construction not be.
- God is loving. In this sentence the verb be is functioning as a copula or link verb - there is no action or state, the complement is only providing information about the subject. Link verbs are only followed directly by nouns or adjectives.
Same with the next two sentences, the meaning of the verb changes from one construction to the next.
- Wind blows. Present simple. This could mean, as commentary, that the wind is blowing or it could just be a statement of fact. In either case the meaning is about the wind itself.
- Wind blows the reeds. The meaning here is about the effect of wind on the reeds, not the wind itself or it characteristics. A more precise representation of the meaning would be to say, "The wind moves the reeds."
The idea of incomplete predication would be better represented with a verb like belong or carry to give both a transitive and intransitive example.
- I carry. - This is incorrect because we always carry something - the verb is not meaningful with out its object complement (transitive).
- The book belongs. - Also incorrect because the verb is incomplete without its complement, always a prepositional phrase. The subject belongs to someone, in someplace or on some surface.
Presently I am looking for strictly intransitive verbs that require a complement, which by necessity means an adverbial complement, most often a prepositional phrase. My list, so far is quite short, go and belong. Go can take an adverb or a preposition but belong appears to always require a preposition.
- He went to Mary's house.
- He went quickly.
- The books belong on the shelf.
And so on.