Generally, if this is a relatively new cross-disciplinary area, this will start as a very small group of institutions. If it's a fruitful area, that number will grow quickly, and among the early adopters might well be some of the best universities.
And yes, to set up these programmes in the first place, does indeed require buy-in from professors and top-level university administrators, so there are tenure-track professorships interested in applicants with those sort of cross-disciplinary backgrounds
What is it like to study in a new cross-disciplinary area?
There are a few things that make it different.
You might find yourself building the foundations. A lot of the work might be much more exploratory. It can be the wild west, with few established paths and no signposts; and you may end up making up the rules as you go along.
That is to say, established fields tend to have well-defined protocols for things like data collection; and a proven set of tools to work with. Whereas in a new cross-disciplinary area, you're more likely to be building the basic toolkit from scratch: writing your own protocols starting from bare bones. There will be things you can take from each of the disciplines that you span, but combining them will be untested ground.
Some of the papers you write may end up being foundational for the new cross-disciplinary area, and highly-cited for years to come. Even though the work they contain, might seem fairly basic to you.
It can be lonelier. Scarier. More exciting. Harder to get funding. Or easier to get funding. Your reading will be broader, as it will span journals across more than one discipline, and you won't find enough journals or conferences that are closely-enough targeted at your field. You might end up starting your own conference, just to help build the platform.
disclaimer: I do work in a new cross-disciplinary institute, but I do not work in computational social sciences (though one or two of my colleagues are indeed computational social scientists)