With the acquisition of Andre Schurrle and the return of Kevin de Bruyne, Chelsea's options in attacking midfield have swelled. The depth hasn't exactly increased -- the two incomers are counterbalanced by the departures of Yossi Benayoun and Marko Marin -- but it's undeniable that the Blues have gotten more talented this summer. And that may well mean less playing time for Victor Moses.
Combine that with Roberto Martinez moving to Everton and his fondness for reuniting with old players, and you have a story. Everton may well have been interested in picking Moses up on loan earlier this summer, but the that any prospect of a deal has vanished. They cite Chelsea's refusal to consider anything but a permanent transfer (asking price £8 million) as the reason the talks collapsed, but the answer is probably more straightforward -- merely consider the presence of Echo are now reporting Gerard Deulofeu at Goodison Park.
Martinez has strengthened his wings with the addition of the Barcelona youngster, and would therefore have no real need for Moses to come aboard any longer. I'd also imagine that there was some reluctance on Chelsea's part to let Moses go, as he's the only wide player they have who fits the mould of a traditional winger.
If I had to guess, I'd say Moses plays a not insignificant role next season, which I think is a good thing. He's an underappreciated, useful player, and he's young enough that we can expect big things from him.