The year given in the trailer seems to indicate that it's a sequel to SSV/Zero (1786) and a prequel to SSI-IV (1788).
Other clues include the fact that you can see Gaoh (the boss of SSV/Zero) in that painting (guy with the big spear on the horse).
Because it's still doing good business with all the DLC as well as the arcade version. Then there's the fact that the game still has a thriving competitive scene that currently has it's own dedicated eSports tour. The game's in a fairly decent place at the moment.
Indivisible is the upcoming action-RPG from Lab Zero, makers of Skullgirls who's team has the FGC's own @Mike_Z . The game is a mix of Valkyrie Profile's combat but with Super Metroid style platforming and exploration.
Additionally, Secret of Mana composer Hiroki Kikuta is doing the music for...
Rendering power. Since the all 1P thing happens only in head to head setups, then it's using 2 arcade boards (the PS4 based System 478), one to render each scene. Presumably, everything off camera isn't rendered to keep things running at 60 fps the entire time.
It's YouTube's Content-ID flagging everything that uses footage from the leaked trailer.
Maximilian already stated that Capcom has allowed him to repost his stuff.
http://www.neogaf.com/forum/showpost.php?p=142463857&postcount=49