The fly in the ointment ‘in my opinion’ is the Boeing KC76, that has tied up production of the excellent B767-300.
If only the USAF has not bowed to political pressure and ordered what they wanted in the better suited A330. Then airlines would be free the order the Boeing. But that line is tied up.
Where did you come up that? KC-46 production is slated to be slightly more than 1/month - Boeing has the capability easily to produce 767s at five/month, and could go up to seven/month with a little work. Total 767 rate is currently being increased to 3/month (including the 767-2C, which gets turned into the KC-46), and as noted above they can easily go higher if there is sufficient demand.
The 767-400 flight deck is a non-starter - it's been OOP for 15 years. The rest of your post is similarly uninformed...