According to this, http://en.wikipedia.org/wiki/National_Comics_(series), there was talk of reviving certain characters into New52 like Kid Eternity, who seems to have a cool power. Did this just fall by the wayside?
Well, there’s really been too main attempts to get the people interested in the characters, and we’ll cover both below!
Between July and October in 2012 DC released four one-shots, one a month, as mentioned in that link, under the titles National Comics – Eternity #1, National Comics – Looker #1, National Comics – Madame X #1 and National Comics – Rose and Thorn #1.
It was all a bit weird though as Looker would also make a cameo elsewhere, Rose and Thorn was just sort of average and Madame Xanadu was already appearing in Justice League Dark, and there seemed no continuity between the two, even though I liked the one-shot version more.
Kid Eternity – pictured above and to the right – actually got a real update, concept wise, and was actually the most enjoyable and the one I hoped would be ongoing. I reread it just recently and it still really hooked me in. Anyway, the point is that nothing more ever came of these series. Below you can see the cover art for Looker, Madame X and Rose and Thorn.
Now, at this same time, you’ve got a few more attempts at getting people excited in the old National Comics characters with another bunch of limited series, this time around the Freedom Fighters. They were The Ray #1-#4 (Dec 2011-Mar 2012), Phantom Lady #1-#4 (Aug-Nov 2012), which also featured a new version of Dollman, and The Human Bomb #1-#4 (Dec 2012-Mar 2013). These feature new versions and origins, but all end with them being recruited by a new, now black, version of Uncle Sam for a team he’s putting together… and then nothing.
So, the characters certainly exist in the New 52, they’re just being underutilised. It would be cool for some of them to get more time – I especially liked the new versions of Kid Eternity and The Ray – but there’s nothing announced in the pipeline and and as /u/johndesmarals says, DC seems to have been scared off from anthology series.
There’s also the hope in using the multiverse because as /u/watwait says, an upcoming issue of Multiversity is set to feature an earth with Uncle Sam and the Freedom Fighters, one imagines similar to the old Earth-X, and at the end of Superman Doomed #2 we see a bunch of splinters of various realities, one containing Uncle Sam and Plastic Man fighting Nazis.
tl;dr – nothing in the pipeline at the moment, but we can only hope.
Hope this helps!