Tokyopop has announced on its Facebook page in the wake of its shutdown (see “Tokyopop Closing”) that the rights to its uncompleted manga series (like the recent cult hit Hetalia) are reverting to the Japanese owners, to do with as they wish.  Their options will be to end U.S. publication or to find another U.S. licensee. 
The ranks of U.S. manga publishers seeking new licenses has shrunk substantially in recent years, which makes the options for Japanese creators looking for U.S. publishers much more limited than they were a few years back.  The manga publishers still in the market include Viz Media (which as a subsidiary of Shogakukan and Shueisha is tied to those companies), Kodansha (publishing its own titles, distributed by Random House) and its subsidiary Vertical, and Del Rey (which still publishes a handful of Kodansha titles on its own).  Other, more independent publishers include Dark Horse Comics, Hachette’s Yen Press, Bandai Entertainment, Digital Manga, Seven Seas, and the occasional title from a few outliers like DramaQueen (which actually got a title out earlier this year).