We have just looked in class at this passage and how the split at 21 is not correct and has huge pastoral implications, which we did not look into further. We have looked at the grammar just briefly and how at 18, the emphasis on being 'continually' filled with the Spirit is about a habitual daily filling. The same grammar works through the 'speaking' and the 'submitting'.
At 21 there is no verb, so women are instructed to continue submitting as men also lay down their lives. Instructions to children and slaves work in a similar way so that there is mutual submission. All of this is done to the Lord. Lord Jesus. Mr Grudem does different things with this verse.
What about 'submission' (better, 'being subject to)?
What is hypotass?
Origin is military: setting things in order (under one another).
In the NT the word is always passive, unless God is the subject - he is the only one who does the subjecting. It cannot here mean 'obey' (as per the marriage service), since it is in the context of all being subject to one another. See Col 3:18 for contrast between submission and obedience ('hypakouo').
Emphasis appears to be wives submitting to their OWN husbands (v22). Example of Christ's headship (v25) is that of self-giving and life-offering, not authority.