GINOLJC, to all
I'll answer both, yea all of your question,
#1. no I'm not a trinitarian, nor a oneness proponent? Diversified Oneness is totally different...
#2. the Spirit Diversified himself as the "OFFSPRING" in flesh. what was begotten was flesh, the only begotten of the Spirit is the body he shared himself in....

, you know nothing of God and his workings.
now your #3. glad you asked. I'm going to give you the short and stright to the point, now follow.
"The subjection of Christ
within God".
did you see that "
within", listen, 1 Corinthians 15:27 "For he hath put all things under his feet. But when he saith, all things are put under him, it is manifest that he is excepted, which did put all things under him. 28 And when all things shall be subdued unto him, then shall the Son also himself
be subject unto him that put all things under him,
that God may be all in all"
the whole purpose of Christ being subject to God is that "God may be all in all" .... Right.
1 Corinthians 15:28 it says for "the Son to
BE Subject" ... Right.
this is your first mistake, because you think that "be Subject" means UNDER, don't you...

.
well wake up because it don't. did you see that verb "BE" before Subject, which it modifies the word subject.
Listen up,
SUBJECT: G5293 ὑποτάσσω hupotasso (hoop-ot-as'-so) v. According to Noah Webster's 1828 Dictionary of American English. if you don't have the dictionary, here's a link to it.
Websters Dictionary 1828 - Webster's Dictionary 1828 - subject
the Greek word here, G5293 ὑποτάσσω hupotasso, this word is used as a verb, and not a noun. so scroll down to
SUBJECT, verb transitive (that will alert one quickly, the action of a person, and not the person themselves). as a verb one can quickly see, or understand what subject means here in context. Look at Definition #2, To put under
or within the power of. lets look the definition and understand this revelation. according to the definition of subject in the Noah Webster's 1828 Dictionary as a verb, it means 2. To put under or
within the power of. (there is our revelation, “
within” within the power of). lets back this up with our second understanding. G5293 ὑποτάσσω hupotasso (hoop-ot-as'-so) as a verb according to Mickelson's Enhanced Strong's Dictionaries of the Greek and Hebrew Testaments which means 1. to subordinate
2. (reflexively) to obey
[from G5259 and G5021]
KJV: be under obedience (obedient), put under, subdue unto, (be, make) subject (to, unto), be (put) in subjection (to, under), submit self unto.
please notice, the KJV can translate subject, G5293 ὑποτάσσω hupotasso, as be under obedience, which bring us to our second understanding. lets see this in scripture, Matthew 26:42 " He went away again the second time, and prayed, saying, O my Father, if this cup may not pass away from me, except I drink it, thy will be done”. now here is the revelation. the Lord Jesus is God “OWN” arm. scripture, Isaiah 63:5 " And I looked, and there was none to help; and I wondered that there was none to uphold: therefore
mine own arm brought salvation unto me; and my fury, it upheld me”. so being his “OWN” arm it is through, or “
within” the agency of the Lord Jesus Christ that his, (GOD), OWN “will” is done, hence the obedience. this is proven out in the definition of G5293 ὑποτάσσω hupotasso itself WHICH IS THE ROOT of subject. the definition also states from G5259 and G5021, lets see what G5259 ὑπό hupo
(hoop-oh') states,
1.under
2.(with the genitive case) of place (beneath),
or with verbs (the agency or means, through)
3.(with the accusative case) of place (whither (underneath) or where (below) or time (when (at)) In the comparative, it retains the same general applications, especially of inferior position or condition, and specially, covertly or moderately.
[a primary preposition]
KJV: among, by, from, in, of, under, with
examine definition #2 above carefully, it said, when used "WITH" verbs. there is our conformation,
the agency or means,“through”. and
“through” is synonyms with “WITHIN”. so when G5259 is use in VERB form, meaning
with a verb as in “BE” subject as here in 1 Corinthians 15:27-28 then it is understood to be used as the “agency or means, through”.
if you don't understand I suggest you go back and read it again.
Now, knowing this, that the verb "BE" used before Subject, modifies the meaning of Subject. when used with a verb "BE", Be subject means "WITHIN".
NOW, we see why our Lord is God "ALL IN ALL", as the last part of 1 Corinthians 15:28 says,
"that God may be all in all".
now the conclusion:
to be all in all, but at present he's the diversity or as the Greeks say he the G243 Allos of himself, or the numerical difference of himself, meaning two... (Father & Son)...

.
Now to answer you Question, "
Who is the Son turning the Kingdom over to in 1 Corinthians 15:24-28? Who will the Son be subject to at that time? Himself? "
I know you're feeling a little shame right now finding out "BE SUBJECT" means within...

.
but don't because you just didn't know. but now you will. listen up,
since it's a numerically two, (Father and Son) remember the Father is spirit, (subject, abstract), and the Son Flesh & Bones, (object, concrete), so how do God be
ALL in ALL. here's how. again I'll make it short and to the point. the term for a NUMERICAL DIFFERENCE is called DIFFERENTIATION. question, "what is the OPPOSITE of DIFFERENTIATION?" since the process of “ANOTHER'”, is the sharing of Spirit, (the offspring, the Son). so, what is the opposite of DIFFERENTIATION, answer, "ASSIMILATION", hence the "WITHIN" God to be "
ALL in ALL".
now do I have scripture to back this up? yes, Colossians 2:9 "For in him dwelleth
all the fulness of the Godhead bodily". NOW ONE MORE FOR SURETY. Colossians 1:18 "And he is the head of the body, the church: who is the beginning, the firstborn from the dead; that in all things he might have the preeminence.
Colossians 1:19 "For
it pleased the Father that in him should all fulness dwell".
HOW MUCH FULLNESS? ALL OF IT... yes the Lord Jesus is the Father in Flesh. and guess what, when he, the Father, the Spirit deliver up the Kingdom unto him, how many FACES will you see? let's check the record, Revelation 22:3 "And there shall be no more curse: but the throne of God and of the Lamb shall be in it; and his servants shall serve him:
Revelation 22:4 "
And they shall see his face; and his name shall be in their foreheads".
how many Faces will we see? HIS, meaning only ONE. ain't God Good...

.
see how easy that was? if one just search the scriptures and research out these word out then one can KNOW God, not LEARN God. let the Holy Spirit Reveal himself to you.
see, a long, long, long time agao a JW asked me that same question, for he understood what I saying concering Diversified Oneness, that one question he had left, the one you asked. and it changed him.
hope you learn something. Peace in Christ Jesus.