One of the most startling things about the new findings is the apparent lack of heavy elements. The early universe was full of big blue stars, gas bubbles, not the heavyweights of the present. The new question is how these underweight stars supported the process of the formation of elements heavier than hydrogen and helium, let alone huge galaxies.
The Hubble press release
A longstanding problem with these findings is that it still appears that these early galaxies did not put out enough radiation to "reionize" the early universe by stripping electrons off the neutral hydrogen that cooled after the Big Bang. This "reionization" event occurred between about 400 million and 900 million years after the Big Bang, but astronomers still don't know which sources of light caused it to happen. These new galaxies are being seen right in this important epoch in the evolution of the universe.
What’s been discovered has had the odd effect of confirming the hierarchical formation of heavier elements and bigger galaxies, but the ratios of size, nature and number of galaxies to space aren’t explaining a lot.
The researchers are currently looking for a theory which bridges the proto-universe of the distant past and the current universe of giant galaxies and huge galactic clusters. The problem is that the physics have to provide a working model of the energies required.
It’s like getting a galaxy from the emissions of a lighted match. The numbers don’t add up. Current theories include waves of galactic creation, quasars, mini black holes, and other “turbo” versions of energy production.
The formulation of any theory will face major hurdles. Theories will need to produce a working model of the current visible universe, and its drastically different nature. “Dark energy”, the usual explanation for everything at the moment, is also conspicuously missing from the new information. Dark energy also has to have a working lineage in universal evolution, for the theories about dark matter to hold up.
The probability is that a new dynamic will be discovered, showing the gravity/mass/space/accumulation factors in a logical pattern. The track record for galactic evolution so far is that all theories have to be revised, usually extensively, with reliable models slowly forming in the rear of the general brainstorming.