A new air-only fighting game? Can't say I'm thrilled - a fair share of what made HM so kusoge was the aerial movement itself and the inherent problems it caused, notably:
-very slow gameflow in comparison to 12.3's fast-paced action due to the 8-way movement, floatiness, less bullets and difficulty at pinning down opponents
-popularity system - they *had* to somehow compensate for guard being nigh-impossible to break, so they WILL have to implement *some* heavy game-changing penalty for blocking in ULiL, lest everyone would just get a couple of hits and then turtle for the rest of the round (hope it's just some heavy weakening of guard durability as opposed to flat-out alternate win condition this time around though)
-jumping up and down necessitated getting rid of quarter-circle and DP motions, and subsequently the inclusion of the godawful 8-card direction decks from HM - having to take skills, spell cards, system cards, differences between skill directions AND faiths into consideration when building an 8-slot deck was far too much. I always ended up either never using half of the characters' options, never using system cards, not picking correct directional skills that turned out to be essential to the characters' gameplan after I've checked the wiki, being unable to set up both skills and faith that I wanted at once or being severely screwed by muscle memory when I tried to correct any of the above or to just experiment with options. Not to mention combo notation problems. Either set up fixed inputs like IaMP or SWR-style decks if you want me to play this.
Welp, luckily they can easily fix the lesser problems HM had - such as small roster, mere 3 spell cards per character, useless Last Words, poor code optimization or boring character mechanics (notably Koishi and Byakuren, who stick to a single skill 99% of the time from what I've seen on tournament vids - prolly due to their mechanics denying them the option to choose a correct skill for the situation on the fly).
Still, in my humble opinion most of the above need thorough adressing *in addition* to keeping the entire HM cast in and adding some popular characters such as Mima for this game to be remotely able to be a contender against Soku in the fanbase's eyes - *removing* characters from HM and replacing them with different ones instead of expanding the roster will be a deathblow to that end.
And the piano... welp, the randomness of it reeks to me of either SWRSoku's weather stupidity or HM's weird system cards. I just hope to god that's a minor option like the latter and not a central game mechanic. Then again, I'm not expecting anything this time around - I might even end up pleasantly suprised as opposed to HM's release.