Yes, oddly guys like Pinkney, Okwuegbunam, and McKeon (Michigan) all digressed as receivers last season compared to seasons before.
I think Hopkins can also be a stud, and you're right, he's going to have to test well to move himself up in the draft.
A couple small(er) school guys I like are: (1) Harrison Bryant (FAU) who had 61 receptions last year and at 6'5", 240 lbs and a 4.7 forty, he seems like with some NFL coaching could be something special, (2) Matt Bushman (BYU) had 49 receptions as a sophomore, 29 as a junior, 47 as a senior and has good size at 6'5" 245 lbs and speed (4.7 forty), and (3) Adam Trautman (Dayton) who had 70 receptions and 14 TDs last year and is a 6'6", 250+ lbs guy who runs around a 4.7.
I think the biggest weakness in Kmet's game is his speed. He's listed as a 4.85 forty. He's got the size, the strength, the hands and the 'football player' things going for him.. he seems to play faster than that, but it is never easy to judge against college competition compared to the NFL. Regardless, I think he's gonna be a very good NFL player.
For the Colts, though, with Doyle already in place... I think we'd almost be better off with a faster guy who can almost by a hybrid WR/TE (which Ebron kind of was in year 1 in Indy).