Chelsea will be done with the Asia leg of their preseason expedition in about a week, at which point the squad will fly to America. But it's not going to be the same squad -- there'll be some chopping and changing as we get closer to full strength and the youngsters depart.
In Asia, it is very much a case of getting through as many basic principles of play as possible, so that everyone has a grasp of what is wanted, and in America that will go on a level. Six young players will depart and six very senior players from the Confederations Cup will join, and the whole thing will move up a gear.
-Steve Holland. Source: ChelseaFC.com.
The very senior players in question are presumably Juan Mata, Fernando Torres, Cesar Azpilicueta, John Obi Mikel and Confederations Cup winners David Luiz and Oscar, which leaves Kenneth Omeruo out (poor Kenneth Omeruo). The departing six aren't as obvious, but I'd suspect we're looking at Bertrand Traore, Wallace, Lucas Piazon, Nathaniel Chalobah, Josh McEachran and Islam Feruz. But I had to check that that was six players about four times, so I'm not sure my opinion's worth much at the moment.
Presumably some of that group will be heading out on loan and some will be joining up with the under-21 and youth teams. Either way, going on tour with the big boys will have been another good experience for them as they develop. It's not going to be long before a few of them (I'm looking at you, Chalobah) stick for good.