if they did, his dream to become a pokemon master will be reached and will have no more reason to travel
I'd like to see him win the Kalos league only to lose to the E4. It would be nice to see Ash having something to show for his 16 years. But another part of me says no since that would only set our expectations too high for too handle him losing again.
But to be realistic, I know it can't happen. Winning a league might not make him a champion or master, but writers will never consider it unless they are forced to wrap it all up, same goes for the timeskip people want because they will be in a position in which they are forced to put effort into their writing. That's the reason any form of progress is a terrible thing, people will focus more on the plot and characters and less on the Pokemon of the week.
Ash will never win a league as it would resort in the end of the show. Ash should of won the Sinnoh league but you know, Tobias and his legendary Pokemon.... As long as Pokemon anime keeps making loads of "Money" then it shall never end unfortunately. Thus why I stopped wasting my time with the Pokemon anime after DP ended.