Salt Lake has all of the ingredients for success: state capital, big research university near downtown, good existing public transit, totally-rebuilt international hub airport with direct downtown rail connection, incredible geography, low taxes, massive green public parks, and very high numbers of college graduates and foreign language speakers.
I think what holds it back on the national scene compared to places like Austin and Nashville is its reputation as the capital of the LDS church. This is actually ironic at this point because it has a reputation among Mormons as the capital of the left-wing gentiles of Utah. Mormons definitely started SLC but they certainly lost the war for it (a story for another time!).
That's not to say SLC isn't booming right now though. The city is unrecognizable at street level compared to when it hosted the Winter Olympics in 2002. The way things are going, it will be unrecognizable again when it hosts the Olympics again in a decade.