I think it would be really good if there was another Naruto Storm game. I know Cyberconnect 2 said Storm 4 would be the last one, but I think it would be quite awesome if there was another entry in the franchise. The Storm games are more liked than Shinobi Striker from what I've seen, there's definitely a market for it.
With so many characters, and the potential to dive into the sequel series too, there's a lot of potential here.
Game Play: Storm 4's game play was pretty good, you could implement the wall-running from the Story Mode/Storm 1, Maybe with more arena shapes than round (with obstacles like Trees, Boulders, etc). The Accessory system from Revolution was pretty neat, I'm not sure why it was removed. Though I think it would be awesome to be able to select Awakened characters from the start (like the PS2 Ultimate Ninjas + Storm 1) too.
Story: Something like Storm Revolution's would be amazing. My favourite part of that game was seeing all the various interactions between the characters you'd normally never see. A premise like this could possibly utilize time (hey, we've had stranger things in the franchise), which could also give an explanation as to how the Science Ninja Tools & VR System has data on characters that long died before they were invented. Imagine Sarada interacting with Itachi, Boruto meeting Neji, Kagura learning what his grandpa Yagura's really like, Kushina meeting Himawari....hell, have it a sequel story and have Boruto meet Mecha Naruto (who's been rebuilt by the Scientific Ninja Weapons Team).
Characters: There's plenty of Boruto characters to draw from, as well as Toneri & some fan requests.
https://www.youtube.com/watch?v=SMtcch90VOE As seen here, the Support-Only characters had several animations and combos already made, they could be finished off if you wanted to. Also, although it's extremely unlikely, you could have the Naruto Online avatars somewhere. They're surprisingly likable characters with way more depth than they deserve (with character designs partially by Masashi Kishimoto), it's a shame they're confined to a browser game (that CC2 worked on might I add) and would be tragic for all that work to not have them in an actual game.
Custom Characters: Like Xenoverse 2 & Shinobi Striker's drawing point, you could also add a custom character (which often reuse resources from other characters, as they often learn techniques from characters in games like this). This could also tie into the Revolution-like Story, letting you interact with the various characters and see new sides to them. They should probably wear a Science Ninja Tool to explain away how they can use Kekkei Genkai and whatnot (Shinobi Striker doesn't really have that excuse, Anyone can just randomly mix and match Kekkei Genkai without explanation). Their move set could either be chosen from a set of premade ones (Jump Force-style), or select from a variety of available attacks (Combo Strings, Tilt, Grab, Jutsu, Ultimate Jutsu, Projectile). If not Custom Characters, you could involve the Naruto Online 5 in the story instead (mentioned in the previous section)
Costumes: Along with returning costumes from the previous Storm games, you could add more costumes based on "The Last", "Boruto", various outfits they wear in the anime and other places. For Custom Outfits, let us recolor them as opposed to randomly obtaining set colors (Xenoverse handles this pretty well).
Longevity: You've been supporting Xenoverse 2 for quite a long time, I'm certain that the Naruto Franchise is one of the few other anime franchises that would be able to successfully do this in all regions. With the massive amount of characters & outfits to draw from, there's countless possibilities. DLC could be fan-favourite characters, characters that otherwise missed out on the base game, newer characters, costumes for the roster & custom character options. And no random scrolls for content. Shinobi Striker suffers greatly from this to be honest, relying too much on RNG to artificially lengthen the game.
Most importantly: ALLOW OFFLINE PLAY!!!
Many, MANY fans were and still are outraged that there's no offline play for Shinobi Striker, along with the lack of content (not really any story mode, there hasn't even been any new missions added since the game released, which you'd think would be a no-brainer).
I know it's a long shot, but I thought I might as well attempt to let Bandai know there's still fans out there that want a Storm 5 (or whatever you want to call it). These are just ideas and suggestions, but I hope you've gotten some ideas or inspiration for a future Naruto game.
I'm sure there would be a lot of fans happy with a new entry to the franchise, me included.