Black holes as frozen stars The idea of fuzzballs formed with strings says that black holes don’t really exist. There is just this big quantum thing that can be built up in many different ways which gives a very high entropy to such an object. The new thing about this paper is now that they calculate the probability for a collapsing ball of matter to transition into such a quantum state. Authors say that while the probability of it transitioning into any one particular state is very small, there are also a huge number of these states. If you multiply both factors that gives you a probability which is close to one, so it’s a very likely thing to happen.

The concept of black holes as a pinpoint singularity was taken seriously for more than fifty years in mainstream physics, despite its apparent reductionism. The introduction of quantum mechanics essentially contradicts it, the problem is, this theory is reductionist as well, so that no one can predict what actually happens inside of black hole with using of simplistic theories. We have some clue from neutron stars, some of which can behave like frozen stars. In this model so-called firewall would correspond physical surface of these stars, which aren't conceptually different from our Sun - but does really apply to more dense objects? BTW Whole the fuzzball concept is everything just not frozen - the fuzzball of undulating strings is concept, which is supposed to be very dynamic instead.

The problem is, there aren't known physical forces, which would keep such an objects apart other than electroweak interaction, which applies inside of atom nuclei to quarks. Also, there are an apparent limits for gravity strength from shielding force perspective. As the shadows of massive object goes smaller, then no shielding and gravity force can apply to it as well. From GUT perspective, the electroweak and gravity forces would converge into something which resembles dense star, but it's not frozen anymore - it merely resembles a giant quantum wave packet or gravitational lens of dense vacuum (a geon) or gravastar) dancing and undulating at place like some fancy crossbreed of relativity and quantum mechanic models. Such a destiny of black holes would merely resemble dynamic undulating stars waiting for their final explosion like Betelgeuse rather than frozen white dwarfs. Also the concept of Steady state Universe eternally recycling matter into radiation and vice-versa would contradict the idea of frozen black holes. See also:

• How the Inside of a Black Hole Is Secretly on the Outside Mysterious “islands” help to explain what happens to information that falls into a black hole. Many ideas about black hole interior aren't so untestable as they look at the first sight with using of dualities concept (holographic duality in particular). I.e. the insight that quantum mechanics both general relativity essentially contradict each other but they tend to blur mutually in a similar way (being extrinsic and insintric perspectives, i.e. low-dimensional slices of the same observable hyperdimensional reality).
  
• Thermodynamics of frozen stars (preprint) By imposing a well-defined set of matching conditions, we find a metric that describes this transitional layer and show that it satisfies all the basic requirements; including the stability of the object when subjected to small perturbations about the background solution. In fact, we are able to show that, at linearized order, all geometrical and matter fluctuations are perfectly frozen in the transitional layer, just as they are known to be in the bulk of the object's interior.
• These physicists say they know what's inside a black hole They don’t say it in this paper, but in principle you should be able to tell apart such frozen stars from black holes with gravitational wave signals from black hole mergers. There have been a couple of claims that indeed something is indeed off with some of those observations, but the anomaly has remained at very low statistical significance.