Big caveat I know this is very much wishful thinking and almost certainly not the direction DL will go.
With that out of the way I personally would love to see this route come to RDU though I'm certain AA would be none too pleased about it (they just upgauged to the 777 permanently citing significant increase in corporate demand).
On the flip side DL is continuing to invest heavily in RDU and if they can even flip 2-3 of the corporate contracts that have business in both RDU and LHR that should provide enough corporate base.
Again almost certainly a no but it's the internet so we can dream right?