Fournette's running style reminds me a lot of former Oklahoma RB Marcus Dupree. Dupree was 6-3, 230 (bigger than Fournette's 6-1,230), and as Barry Switzer said, "could run over people, around people or through people". He was very fast, and very strong. But he had trouble keeping his weight down and Switzer criticized him often for being out of shape. Dupree left Oklahoma after competing in the Texas game his sophomore year, and was essentially never heard from again....at least not until ESPN did their "30 For 30" piece on him recently.
Will Fournette "burn out" like Marcus Dupree did? Obviously we don't know, but Fournette's running style is very similar, and could eventually make him susceptible to injury IMO.
By the way, Fournette's freshman season was not impressive...at least not until his bowl game performance against Notre Dame.
https://en.wikipedia.org/wiki/Leonard_Fournette