There is absolutely no indication that the series was axed or prematurely ended. This ending is most certainly the author's intent regardless of how you feel about it.
I kinda want the next one to be ended after a time skip where we, the readers, do not in anyway find out the results of this match and these two boxing idiots are just happily reminiscing about it.
Like 30 years later as they watch their boxing idiot kid(s).
Well, when everything is rushed like this it feels as axed for sure.
Not saying that this ending is badly written, just that the manga could have progressed for a longer time without problems.