Mitchell Juergens (Will his role diminish? Probably a bit--but you don't go against a kid like this.)
Devon Blackmon (Will this dude put it together?)
Colby Pearson (Will he stay healthy?)
& Trey Dye. (Is he special enough to earn more than mop up?)
(If Kurt Henderson was truly in contention for a role he woulda played more last year, IMO)

The only WRs who have solid roles tied down, IMO, are
Mitch Matthews (of course) (Definite starter)
Nick Kurtz (Probable starter)
& Terren Houk (Probably not a starter in a 3 receiver set, but will play a lot--even more than last year, I'd think)

mutu.