If Fellaini went, my preferred choice would be Leroy Fer as a like for like replacement. As for other positions, Bruno Martens Indi (CB), Nacer Chadli (winger/acm) , Dusan Tadic (winger/acm), Wilfred Bony (striker), Adem Maher (acm). That's the realistic ones I feel we have a chance of getting and would improve our team.
Sadly not as clued up on the Belgian league anymore as that league isn't showing on the open channels anymore.
Edit: Filip Djuricic and Alfred Finnbogason of SC Heerenveen are also worth having a look at. Same goes of course for Kevin Strootman and Marco van Ginkel. Sadly those two might not be that 'realistic'
whats he like at being forced to play out of position all season without complaining, and then slated and sold by fans without just cause?