Trust me, having watched a lot of very qualified people struggle through the residency process, who you know and where you're from matters a whole lot more than you might be comfortable believing, especially for something like derm or plastics (the applicants for these residencies represent the cream of the crop - AOA, top board scores, research coming out the wazoo - and even then, a good 20-30% of these students won't be able to match). This is all coming from a guy who doesn't give two ****s about pedigree.
Oh, there's no doubt Dell is going to be the UT system's pride and joy, and in time, it's going to be great institution. The thing is, there is a whole lot more that differentiates Dell between other schools, and it has to do with a lot more than time. Brackenridge is never going to be at the level of Parkland/Ben Taub, because it's not designed to be the same as those hospitals. Unless the mission statement of the school has changed recently, I believe that Dell is going to put a lot of emphasis on developing clinicians with training/education that extends beyond the traditional clinical curriculum (where it can take full advantage of UT'-Austin's numerous graduate schools and existing institutional resources). Dell is going to be different, and that's a good thing. But medical schools aren't one size fits all, and incoming students need to be aware that these schools are going to have their own quirks/strengths, some of which will align better with their career goals than others.
It would be doing a disservice to the students applying/accepted to assume that they'll be able to reap these future rewards before they graduate. Austin has some unique challenges. For example, they've run into some difficulties setting up cardiology and heme/onc fellowships at Brack because the private groups that staff the hospital would prefer not to have fellowships there (long story short, it means less money for them). Setting up a department takes time, and I can only imagine that trying to do so while navigating some complex politics will take even longer. It's easy to lay out a roadmap for the future ... it's a lot more difficult to implement it. Heck, when I first started at UTSW, I was told that the new Parkland was going to be finished by the middle of my second year ... it didn't get completed until my 4th year, and I haven't done a single rotation over there
Like I said before, I would have gone to Dell if it was around when I was applying, but the challenges of establishing a new school are not something that I would dismiss out of hand as a minor concern. Dell is going to attract a strong crop of candidates in their first year class on the basis of the name, location, and potential of the medical school, but students need to go into with the understanding that their path may be a lot bumpier than if they had gone to a more established institution. They'll need to decide if the opportunities of being the first class outweigh the potential challenges/risks.
tl;dr take the challenges of a new school seriously, but also consider the potential opportunities of an institution affiliated with one of the most resource-rich campuses in America