Lol you're right, It's not actually confirmed.

Anyway he certainly looks older

ASH IN BLACK AND WHITE SEASON

ASH IN THE XY SERIES

ASH WITH HIS RIVAL SAWYER (WHO IS 10)

Ash isn't 16. He was 10 in BW. He didn't age 6 years from 1 gen to the next.

Wait did Ash already confront, battle, and defeat the evil team in the Kalos yet in the subbed episodes? Last episode I watched (forgot how it went) was the one after Ash got sick and Serena cosplayed as him. I sort of forgot about the show after that lol. 

Oh and she pulled the cosplay off well!

Actually, it is possible since BW had four seasons (there were 2 games based on that gen) and XY has 3, so, there are 6 seasons between the first episode of BW and the XYZ season.

Black and White Best Wishes

Black and White Rival Destinies

Black and White Adventures in Unova

Black and White Adventures in Unova and Beyond

XY

XY Kalos Quest

I don't know about the age of 16 thing, but I'm also hype for the Kalos League. These last several episodes have been great development for Ash's character and his bond with Greninja.

Throughout the XY and XYZ series, Ash has really turned the corner and has sustained a competency that has only really been seen at the Sinnoh League when he went to the Top 4 while beating Paul and defeated two legendaries. Some, who have been watching the show, would say he's even better than his Sinnoh League self. His team is pretty solid, Ash Greninja is pretty interesting, and Ash is battling smarter than he has ever been. If you wanna see how, check his gym battles, his second battle with Diantha, and some of his rival battles.

Now will this translate to him being champion? I don't know, but I would give him a great shot. Possibly his best shot ever since he started his journey.

I know, I was just saying that the gap between two gens doesn't necessarily need to happen in one year.

He should get Charizard back to win the final. Also get Brock and Misty back. MA NOSTALGIA!