One thing that Dallas has been known for is large corporations. We have some of the giants here. (AT&T, TI, American Airlines, HP, Exxon, etc.). In regards to the talent here, we have a lot, however much of it, at this time, is skill sets that corporations look for mostly(Java, .Net, etc.), not necessarily startups. As an employer here I can tell you after trying to hire some front end devs a year ago and then recently, a year ago, it was hard to find many good devs that knew much about creating single page apps (specifically React), however as a few months ago, we were flooded with people who had worked with it. So, I see that as positive. We have many smart people here, and combined with the fastest growing economy and business environment in the US, Dallas is a super attractive place to start a company.
Note: I consider a startup a small-business, or any company that can attract customers from larger/older companies with new/better/improved/simplified products/services. I know many people only consider the "unicorns". But I'll take our vast number of small businesses and "start-ups" over a couple of unicorns any day.
Also to note: I've seen many people moving here from Austin, including their small business/start-up, recently. This is not statistical or any evidence of anything, just an observation.