I was playing a whole bunch of Cave shooters for the first time yesterday (Dodonpachi, Ketsui, etc) and it struck me. The PC demo of XYX I have has a number of things in common - among other things, numerous bullet patterns and types of bullets seem almost identical to bullet patterns in the Cave games. Also the tightness and speed of how your ship handles when moving side to side and up and down in PC XYX feels like these Cave games.
Additionally, from looking at the NG Dev Team video, there is an addition in the neo version that is not in the PC version - namely, a big ship comes in the beginning of the stage to "drop your ship off" to start the level. This is another hallmark of many Cave shooters such as Dodonpachi and Ketsui. Finally, the graphic style and the tiger head fireball are reminiscent of Truxton, a game made by Cave before Cave was Cave! The game over screen that fills in with skull tiles in PC XYX is almost a direct copy of this same thing, which happens with nearly identical looking skull tiles in Truxton 2. So I think it is safe to assume that this game will have significant influence by the many popular modern Cave shooters, while keeping some style and references to older Cave related shooters.
Another reasoned speculation I have is that the game will be 1 player only (even though PC XYX is 2 player). Aside from the fact that NG Dev Team has never made a 2 player game to date, and that this might be something of a NG Dev Team quick release where they don't want to spend the time to make it 2p - in the NG Dev Team video, your ship is towed in the center behind the large ship, whereas in 2 player Cave shmups your ship is towed on the left for P1, and on the right for P2. Additionally, the way the bombs, lives, score graphics are presented in the NG dev Team video seems to imply that a 2P will not be available as these details are spread around all sides of the screen rather than being relegated to one side of the screen only.