well, Mirror War is still around if anyone's concerned. From Steparu's vid, it looked to be Valkyrie Sky 2.0, so I hunted down the site and got past the annoying event teaser thingie and thought they decided to turn it into a stereotypical 3DRPG. However...nope! Linksauce: http://www.mirrorwar.co.kr/info/guide05_04.aspx (look down a bit)
Edit:
But to answer the question on Valkyrie Sky, highly doubt it. Viral stuff and petitions have been tried time & time again to bring stuff back or at least release the source code so people could make private servers if the companies aren't using them anymore, and rarely do they ever work. n2m Valkyrie Sky honestly didn't have that big of population when it was around, which is a shame really given how much the internetz love Touhou and other danmakus.
double shame as well as the game itself was good for a danmaku. each class felt unique, had a melee class that worked in a way, and various ways of attacking that wasn't just "how many ways can I shoot straight forward". music was pretty good as well. I call BS though on the Buddha boss I saw in a vid, where it was basically a race to do as much damage as possible before you're smothered by a chasing bullet blob.
Edit 2: misspelled Valkyrie. shaaammmeee
Edit 3: specified release date a bit more since it's actually a fairly recently launched MMO. also Steparu says that it's doing better than VS right now according to his 2012 awards article, and they got a publishing license with Indonesia earlier this month, which means there may be hope that we'll be able to see it overseas for all to play eventually.