I think Prefontaine was a leap ahead for American running (I mean, he still holds the esoteric 3- and 6-mile American records.) He was part of a contingent along with Shorter, Ryun, Rodgers, Liquori, etc. who repopularized running during a period of cultural change.
My honest guess is no. I think if he is there, Dixon and Brendan Foster don't go for broke in the prelims of the 5,000m, and some combination of Viren, Foster, and the New Zealanders outrun him.
(None of them were particularly competitive in the slower final except for Rod Dixon, who got robbed of a bronze in a more spectacular manner than Prefontaine.)