Miami is still so far behind the curve in creating middle class jobs, housing, or in providing amenities to attract/retain middle class residents or even young non-rich residents (young professionals) downtown. The bulk of housing going up is still exclusively high-end/luxury housing and there is a dearth or complete lack of affordable or below-market rent/cost housing going up or in existence (which, to be fair, is a national problem affecting most cities). The downtown area's first major grocery store is only a couple years old (Publix Mary Brickell Village, besides Midtown Miami miles away this is the only major full-service grocer in downtown, evidence that there isn't a huge concentration of permanent downtown dwellers), but in terms of the retail coming, the bulk is contained within two contained mass developments and geared towards tourists and the wealthy.
In terms of office/jobs, there is still a severe lack of jobs for young people and a lack of office development to demonstrate this out.
I digress, Miami is seemingly turning around in general and downtown, specifically, but in my opinion and in my experience Miami is an outlier of a city in this country when it comes to just about everything. Los Angeles is so often compared to Miami, though I find so many differences. However, LA's downtown redevelopment is much more apropos to the direction in which we so often say Jacksonville's downtown should go once it takes off (if ever that happens within the next 10 generations).