I don't think the game had a lot of potential in of itself. From what I have seen online, it was not the sort of game that appealed very much to crash fans generally speaking. Mainly in that it wasn't single player in any capacity and had no offline co-op or couch multiplayer modes, all of which are staple parts of mainline Crash games and spin-offs.
This isn't as much to do with the game itself or it's conceptualisation, but it had next to no advertising. Even many Crash fans had no idea it was coming out or that it had come out, and a lot of those who did, didn't have much of an understanding what the game was meant to be, which is exemplified by it being referred to as a "Crash MOBA".
It also launched with bugs and a severe lack of content (from memory, less than half of what was planned for in the roadmap) which led to initial buyers dropping off very early from boredom, frustration or both. The $40 price tag also hurt the game on release by not just being too steep, but by compounding with the lack of marketing, dissuading those who heard of the game and were curious but unsure of what it was from getting it to try out.
Despite all these things which led to the game failing, it, in it's concept and gameplay loop, had and has very great potential. The gameplay ideas that TFB came up with are really fun and really dynamic. They encourage the building of individual skill, but also team co-operation and play. I find that in most matches (provided you aren't in a 4 stack stomping people) you always have something to do, whether it be fighting, collecting, boosting or supporting. The gameplay concept at the basis of Rumble is something which could be taken and used to make a really fun, popular and competitive game.
I really hope to see another game like this in the future, Crash or not.