Based on the current and previous themes, goals and audience of the show and the character of Ash, most likely not.
Note that this is all speculation since there is nothing revealed about the future of the show. Ash might just become a very complex, adult Bat-Pirate-Man on Jupiter in the next episode, but I will do my best to explain why one of these isn't likely to happen.
First of, the shows goal. In my eyes the shows goal is to be endless. By never changing anything, never have any overarching story, never developing the character or never putting anything at stake the show have been able to produce hundreds of episodes, and still sell well. (I've already gone over the details of this status quo here: http://pokemondb.net/pokebase/238719/can-someone-explain-this-whole-digimon-and-pokemon-thing). But how does the past of the show effect its future? Well, the show wasn't always about status quo, or endless. Originally there was only going to be one season, and the overall quality showed it. This is not nostalgia or genwuning on my part, in the first 80 episodes we have far more development and character than in the rest of the series combined. Sure it wasn't that lasting and it was mostly the Pokemon that developed, but there was something. That they abandoned this in favour of longlivety is certainly present in the later series. Ageing the characters would mean development and breaking the status quo. A new stalemate could be found but why risk it?
Then we have the target audience of the show, and the nature of Ash. As I brought up in the other question (in short, reference http://pokemondb.net/pokebase/238719/can-someone-explain-this-whole-digimon-and-pokemon-thing) Ash is supposed to be a avatar, a character for the viewer to project themselves onto, rather than being character on his own. Here the target audience is extremely important. The show is and have always been for kids, this have been true since its inception. Most of the time kids can handle change and more dynamic characters, but why risk the longlivety? If Ash were to grow up the core audience wouldn't be able to project as easily onto him. If the target audience were to grow up in any greater quantity Ash might grow up as to keep up with the trend, but as of now the target audience keeps Ash age the same as the audience.
What is also important to note is that the kids are the most profitable market for the shows. Certainly the games can be enjoyed by people of all ages, but the rest of the merchandise, toys, cards and so on are primarily bought by the younger audience. Ageing Ash would thus alienate the most profitable audience.
So in short, Ash is unlikely to age because it would break the longlivety of the show and alienate the core audience.
