I'd imagine Kadokawa Pictures might be difficult with giving the BD rights for Maken-Ki, same with C3 (and all their recent titles) since apparently reverse importation fears are a HUGE concern for them.
Funimation probably doesn't want to do a DVD-only release so they'll wait patiently until Kadokawa is satisfied with the amount of "waiting time" (for what it's worth I don't mind a DVD-only release).
5 out of 6 DVD & Blu-ray volumes are now available in Japan. The 6th and final volume comes out at the end of this month.
I'd guess Funimation won't pick up additional rights until maybe July (Anime Expo announcement) or August (Otakon announcement).
Then it won't see an actual home video release until maybe December. That's 6 months of waiting from the final Japanese volume release to the North American release. Will Kadokawa be satisfied with that time frame?
As for the dub cast...
How can you even begin to cast VAs for a show like Maken-Ki with complex characters?
Kidding aside, I'm sure a dub will be the same standard as an average FUNi dub.
I'm not super attached to this show so I honestly don't really mind who voices who (compared to other anime I'm more passionate about) but just for fun, these are some of my picks.
Like my dub cast speculations for other shows, I like to mix both veterans and newcomers.
Takeru Oyama: Blake Shepard
Haruko Ayama: Leah Clark
Kodama Himegami: Emily Neves
Inaho Kushiya: Lindsay Seidel
Minori Rokujou: Jamie Marchi
Aki Nijou: Lydia Mackay