Psyonix have recently laid out a for the coming months of Rocket League. A few fan concerns have still remained unaddressed, and the game director Corey Davis has taken to Reddit to clear things up a little.
"We think we have a pretty diverse and fun set of alternate modes including Dropshot, Hoops, Rumble, and Snow Day. We’d like to spend time improving those and offering more ways to engage with them rather than putting resources towards yet another addition to the roster", was stated in a Reddit post by Psyonix.

The main concern apparently is that a lot of players go straight back to the default Soccar after taking new or alternate modes out for a spin. The studio is currently still brainstorming how to solve this, but the initial idea is to add more competitive playlists and seasonal rewards to these mods, which should appeal to the more competitively minded Rocked League players. In theory.

These changes still aren't laid out anywhere in official roadmaps because they aren't quite ready for work to start on proper implementation, but they will be there soon enough. Rocket League's February update is going live today, but there was more talk regarding the game's somewhat underdeveloped Custom Training mode, which still has no clear delivery date.
Psyonix have repeatedly stated that they tackle features based on overall priority and not in accordance with any sort of set release schedule. The work is being done, but players may not see the full results until some later point in time.
You can have a look at some of the updates the team has actual release dates for , and the Reddit post in question over on Rocket League's subreddit.

























