The key to the revitalization of the Earth 2/Justice Society concept was that you had Darksied instead of Hitler as the main impetus of the JSA. It was the Darksied War and the fall of the trinity that gave rise to the Justice Society and the world building of the Earth 2 to be this weird steam-punk, after disaster reality.
What was also neat was reinventing these Earth 2 characters with a sensibility towards the New Gods and New God tech. It felt more cosmic, less pulp.
So how you would get back to the Earth 2 concept that was such a neat seller in the first place?
My thought would be to bring in Infinity Inc and sort of merge them with Young Justice and give them the Legion of Superheroes mandate:
100 years from now, while this new earth as settled along familiar lines, we have a new generation of Superheroes taking the mantle of older members in sort of a membership to a new UN Sanctioned team. These young heroes are called Infinity Inc and are representatives of each of the new countries.
Red X from Gotham
Kent Shakespeare from Metropol
Cassandra, Agent of F.U.R.Y. from New Olympiad
Impulse (Bart Ognats) from New Dehli
The Green Flame (Kai Ro) from New Tibet
Redwing and Northwind from Feitheria
The Spectre (Gretta) from Germany
Nuklon (Albert Rothstein) from Greenland
Arrowette (Paula King-Brooks) from Britannia
Stars and S.T.R.I.P.E. (Sylverster Pemberton and his A.I. known as S.T.R.I.P.E.) from Central America
Neptune Perkins (Kaldur'ahm) from Atlantis
You make thngis so clear. Thanks for taking the time!