Just wrote the same in the Gomes thread. Both these two need to be sorted out. They're here, they're settling in nicely, their performances so far show huge promise. Both look intelligent whilst playing and have the trust of the manager to go out and play using their nous. This team will soon approach the level when they can compete against anyone; if they stay, they may well be making a very good decision for themselves as well as for Everton.
I know Zouma can point to a return to Chelsea and Gomes to Barcelona, but a season or two here, will harden them into top players and if they do go, it'll be back to that sort of team, and they'll go back as first teamers, not bench warmers. A couple of seasons here though, and maybe Mr Silva can break through the glass ceiling and keep them around for longer...
Gomes will be a lot easier to get than Zouma, I think.
He clearly doesn't want to be at Barca, so if he continues to settle like he has done, I see no reason why he'd turn down a move. It'd be then up to us to work out a deal with Barca.
Zouma's a bit different. He probably wants to make it at Chelsea, so he'd need some persuading.