Why would they want to replace fabregas? Who will they get who is better?
Doesn't fit their playing style. Isn't popular with their fans. Isn't popular with their coaches. The club has fed rumours to the press about attitude / off-field issues. The only time he's really looked good on-field was when he was playing neat little moves with Messi, but they've hired Neymar for that job now. That'll do for starters.
Against that - they sold Thiago. He won't be forced out, because Messi likes him too much. We don't know if he really wants to move.