The more I think about it, Illi forcing a move seems so out of character. Yes he wants to play for OM but he's been so shrewd, up until this point, around his career. He values Football above all else. There's no doubt in my mind that he will see playing in the PL as one of the 4 main jewels in his personal crown - playing in the PL, for Senegal, in the CL and playing for OM. Why, on the cusp of ticking off one of those major career goals, would he side step, potentially never to return? OM will still be there in 5 years time. Other PL teams, perhaps in the CL positions, will no doubt be sniffing. If he continues to improve at his current trajectory, they will be battering down United's door for his signature in 12-24 months. His place in the Senegal squad isn't going to disappear if he plays in the PL, quite the opposite I suspect.
It just doesn't make sense for someone that's been so singular in their focus, to climb to the top of the ladder, to take a sideways step away from one of the biggest prizes.