With Broly's trailer dropping recently, it marks the end of Dragon Ball FighterZ's second and presumably last season. Presumably the last, because neither Arc System Works or Bandai Namco have even hinted at the possibility of a third season.
That being said, the game is still incredibly popular amongst its hardcore community, and it still pulled in good viewing numbers at the last EVO Championship Series, so the announcement of a third season wouldn't be entirely out of the realm of possibility. After all, publishers like money and DLC makes bank. Stranger things have certainly happened.
Data-miners have found a few interesting tidbits of information in the most recent patches for the game. Back when Janemba was first released, data-miners found four unused IDs in the game files for four currently unannounced characters.
There is also the strange case of a file called "CharaSelect_S3" that the game is specifically told not to load, as well as a folder called "CmnBG_S3" that was added in the games last update.
Of course, none of this confirms the existence of a season 3, but it certainly seems like indication of things to come. Which begs the question... if Arc System Works are planning a season 3, who would they want in it? And who would Bandai Namco consider the most profitable characters to include?