Really like jloomes insight on this formation, though I prefer the exact same tweaks as you have suggested. Unfortunately, I cannot see Dunfield keeping both Osorio and Bradley off the pitch at the start. I agree with jloome that historically Fede has enjoyed more success in areas left-to-centre than right-to-centre. IIUC, the 4-2-3-1 seems to be giving CFMTL issues. In the end, I do not think Terry would even field these set-ups of the formation we seem to want. At best, if he does use the 4-2-3-1, it would most likely be...
------------------Romero-----------------
---Blessing--Rosted-Mabika--Petretta---
-------------Ibarra-----Coello------------
-Bernardeschi--Osorio/Bradley--Insigne-
----------------Mailula/Owusu-----------
I suspect that in the end Dunfield reverts to his tried, tested and true, the 4-4-2...
-----------------TM--------------
---LB/KF---SR/LS---AM---RP---
--FB--FI--JO/MB/BS--LI/JMR—-
-------CM/DK-------PO/CJS-----