Blue in peace here lads.
Koeman will be confirmed tomorrow by all reliable accounts. Talks have been held up due to your end dragging their heels. It seems you were confident Ron would stay in spite of our interest and have spent the last few days approaching managerial targets and working out compensation terms, which is understandable given the narrative that Everton couldn't take Southampton's manager.
Preventing player poaching might not be a great concern for you. Granted, there are one or two that Koeman might want to take along, but the appointment of a DoF and the new owner's own targets mean it's unlikely you'll loose too many. I suppose your biggest concern could be Forster. It's unlikely we'll take VvD unless we sell Stones, which we'll only do if there's an offer significantly in excess of £40m.
Hopefully this won't sour relations between the two clubs too much in the future. I think it's natural that Koeman would want to take the next step and, like at Feyenoord, he will hopefully be remembered as doing great stabilising work with your club as you transition from feeder club to a solid PL outfit. Great progress, really, and your board should be commended.