My two pennies worth here...
I highly doubt that there will be any changes made to the Union Flag if Scotland were to leave (which again, I highly doubt). The original composition of the flag was without the four red bands in each corner, and these were later added to represent Ireland in the Union.
Obviously, Ireland became a Free State in 1922 and the flag was not altered. Although granted, the UK still has several Northern Irish Counties, these were not actually specified by Britain in the Anglo-Irish treaty, but instead those counties exercised their right under the treaty to remain British. So, in actuality, if they had decided to remain as part of the Irish Free State the Union Flag would still not have been altered, as the Crown had given the entire island of Ireland the opportunity for independent rule.
Anyway...enough politics
. I have mixed opinions on the new livery. In my eyes P&O were like Cunard in that they maintained an apparent level of "quality", but I cannot help but look at this new livery with a feeling that it has the typical tacky "cruise ship" air about it. Granted, you'd be a fool to think that any cruise ship company is of the same quality as was such with the ocean liner days of Cunard and the White Star, but at least it "appeared" that way with the old livery.
Kind Regards,
Jack.