Sabin_Stargem: I think it would be possible to do with some stuff from the 90's and earlier, since a fair chunk of that material was pirated by young fans of anime. Fans that now have families and paychecks. Like with how GOG had started with classic games, I think it would be possible to convince older anime fans to part with their money.
Material like:
*Slayers
*Ranma 1/2
*Black Jack
*Astro Boy
*Record of Lodoss War
*Bubblegum Crisis
*Patlabor
*Samurai Pizza Cats
*Mysterious Cities of Gold
*Speed Racer
*Hans Christian's Little Mermaid
Further, targeting niche followings would also be relatively easy, since there is much more for the Japanese to gain, than what they would lose.
EG:
*Rozen Maiden
*Spice & Wolf
*Bride's Story
*The Book of Human Insects
*Ace Attorney (manga)
*The Big O
*The Manga Guide to Physics
*Emma
As for the studios: The 90's materials were already pirated and don't have many modern fans, so they would be relatively easy to convince into trying out the model. In addition to this, GOG could try to wrangle various Japanese publishers when they try to create new game IPs ( Kickstarter, ect), before spinoff material is produced. That would give GOG the ability to "intercept" the producers and get a distribution contract for those items.
The "interception" option is the most realistic path, in my opinion: In order to get at the really good stuff, GOG would need to establish ties with a wide variety of studios and learn how to negotiate properly. Starting with the small fry is a logical starting place for that.
let's see who GOG would need to reach agreements with for the shows listed above as of today (and this is just for US/CA. Also assume companies hold the streaming rights as well): Slayers is OOP save for season 5 (as in I couldn't find it for sale on rightstuf), Ranma needs a deal with Viz, Black Jack needs a deal with anime sols, Astro Boy is Nozomi/lucky penny (rightstuf basically), record of lodoss war is not for sale on their site (assume OOP), Bubble gum crisis Animeigo (crisis tokyo is Funimation which has their own streaming service), mysterious cities of gold I can't find on rightstuf so probably not lisenced.
Patlabor is a combo of Maiden Japan for series and Sentai Filmworks for movie (latter has VOD and streaming services). Speed Racer is another Funimation title which is not yet re-released.
For further down the list for stuff targeting niche audiences the following companies own the rights:
Rozen Maiden: Sentai
Spice and wolf: Funimation
I don't know where bride's story came from as I have no results for a DVD release on rightstuf
see bride's story for human insects
Ace Attorney manga needs Kodansha Comics onboard to sell
Big O-that is tricky. I don't know HOW the hell you would get both Sentai Filmworks and Cartoon Network (they basically own season 2) to agree to sell all the epsiodes DRM free.
I am not looking up the others as they are manga.
Basically, for the shows you listed, you would need to have GOG make deals with EIGHT or NINE different companies as well as at least 3 more for the manga. Of the 8-9, at least 2 will be very hard sells and 1 will be next to impossible. And that is only for the US and Canada!