You're making a rather sweeping statement based on the opinion of a single professor. A quick Google Scholar search will show you that the vast majority of research on motivation still shows that intrinsic motivation very much exists. It's just our definitions of extrinsic vs. intrinsic and the recognition of how the two interact that are changing slightly. See, for example, [1][2][3].

[1] http://www.sciencedirect.com/science/article/pii/S0361476X99...

[2] http://psycnet.apa.org/journals/amp/55/1/68/

[3] http://psycnet.apa.org/journals/bul/125/6/627/