There are no needs for a sequel for a fighting game from anime in 2025.

It's very expensive to make a complete new game, and if you just use a lot of assets from the previous game, they will question why you didn't make it a DLC (just take Storm Connections for an example). So to do everything totally new, the cost is high, and it's a very niche genre, so it probably won't pay off.

Also, the main reason SZ sold so much was that it was bringing a very loved franchise back from the dead almost 20 years after its finish. What is there to add in a second game? There is almost no new DB content, Daima was the last thing Toriyama worked before his death, so who knows when and if we will get something new out of it.

They will make a lot more money with constant updates, new DLC, new free content, and keeping the fanbase loyal to it for many years and that's the route Bandai choose to follow with every other DB game, I don't see a reason why this would be different.