While I don't doubt that Everton would be interested in a player of Capoue's ability, the notion that he could replace or even replicate Fellaini's production is somewhat misleading, especially considering the Belgian's role in the Everton team this season.
Having spent much of his Everton career employed in a deep midfield position, Fellaini has found success this season playing behind the striker as an attacking midfielder. It's in this area where his heading ability and ball retention allow him to do the most damage and it's been a key element to Everton's success.
Fellaini has played so well that it has fueled speculation that Chelsea will match his contract exit clause fee, thought to be in excess of £20m. In truth, although Everton might use the money from a possible sale of Fellaini to finance a move for Capoue, the French international would fulfill an entirely different role in the team.
The 24-year-old Capoue has spent his entire senior career at Toulouse and last year made his breakthrough to the French national team, winning four caps to date. He is a defensive midfielder who is also capable of playing as a central defender. Like Fellaini, he is a big, strong player, and at 6'2", is good in the air, but it would be a major surprise if David Moyes considered him a direct replacement.
Indeed, Moyes probably has Capoue pegged to solve another problem in his team. So far this season, Everton have not looked as strong a central midfield as they have in previous seasons, with Fellaini having moved further forward and Jack Rodwell sold to Manchester City.
The Toffees have used players such as Phillip Neville, Darren Gibson, Leon Osman and Thomas Hitzlsperger in central midfield during this campaign. There's no denying that Capoue would add an injection of both class and physicality to that mix.
Capoue is no mere destroyer. A feature of his game are the long diagonal balls that he plays out to the flanks. From a deep role, Capoue can provide both defensive solidity and use the space available in that area to pinpoint his passes, launching swift attacks.
Moyes is nothing if not a tactically adept and flexible as a manager. He doesn't have the resources to choose just one way of playing and stick to it, instead having to constantly adapt his team structure to match the personnel at the club, as his best players are always eventually sold.
Everton under Moyes have seen many different tactical incarnations and if Fellaini goes, it would be no surprise to see a completely different player such as Steven Pienaar employed in the attacking midfield role, or a 4-4-2 system put into action.
So Everton's attacking options might be lesser without Fellaini, but the central midfield area would be much stronger with the addition of Capoue. With Moyes in charge, you can bet that whatever happens, the pack will be shuffled and Everton will come up aces yet again.