Not being disrespectful to Burnley at all, as I quite like them as a club, but they're almost in a no-win situation so it's better to twist than stick.
If they keep him for a year then he'll certainly go because of his calibre and the interest him, but they will financially have to take a huge hit.
Something they simply can't afford therefore it's in their interest to sell him, yet as you point out it'll very be difficult to replace his vital stature.
I dont think there was any doubt they would sell, they talked the talk, but he was always gonna go, they got very, very good money, we get a very good player, win, win for both.