I think those conflicts occurs anyway!
Of course it would need evaluating, that goes without saving but I think it's worthy of consideration.
I don't see the need to build anymore platforms when the exisiting ones could be rationlised. (Aside from reinstating disused ones)
There are indeed such conflicts at the moment, but that is the very reason why you will find Northern Blackpool and Leeds stopping services on platforms 10 and 11 - this being related to the existing terminating usage of platforms 6 and 7. If those terminating platforms were not available and platforms 1, 0 and A were used for this purpose, you'd actually make the problem worse.
There will be something to be gained when LNER's York terminators are extended to Middlesbrough, which will create capacity on platforms 6 and 7.
It sounds simple, but the answer to creating more through platform capacity, is to stop using the through platforms for terminating trains. From the south end that probably means platform 0 (assuming the mooted increase of XC terminating trains goes ahead), then post LNER extensions to Middlesbrough, you broadly have:
p1/0
XC services via Doncaster - at the right side of the formation for the Main lines at Colton
NT services to Hull - at the right side for services direct via Hambleton and to access the Normanton lines at Colton
p6/7
NT services via Leeds - with direct exit to the Leeds lines, but also flexibility to get to the Mains/Normantons if needed
Huddersfield via Castleford services - in the correct place for the Normanton lines either via the Mains or the Leeds lines
At that stage you have minimised your conflicts, and removed the need for terminating trains to stand on the through platforms. Ergo, you don't need more through platforms, you just need to free up the ones you already have.
From the north it is a bit more awkward as Harrogate services would have to cross the Down route for the ECML to access p8, hence my suggestion of a bay platform 12.
Of course the advantage is that these p0 and p12 could be significantly built off line, and other than inserting a new set of points for each, even if disruptive access is required, only take one existing platform out of use temporarily. They also both do not need any additional footbridge construction.
Is it still? There's buildings quite close to P11. Problem with York is that it's on a fairly hefty curve, otherwise you could slide the (modern-ish) P10/P11 island a bit closer to P9 to make some space on the west. Pity "P8B" (what was P12, looking at an old photo I came across on the interweb) couldn't be used. But I do agree with the idea of separating the via Knaresborough services out from anything else that says Leeds, to reduce passenger confusion.
The land is now more protected than it ever has been. When York Central construction gets underway and the old IECC building is demolished, a greater slice of land will not have buildings on it than is the case currently.