A lot of people believe this is how they will phase Ash out of the anime. Have him win and decide to stop journeying to train to fight the elite 4.
I personally can't see him losing, as it'd send the wrong message to the children. Treating your pokemon (friends) like crap will make you win things, yep, best message ever to do. In past losses, it could be seen as "Paul trained harder, so practice made perfect" but now Ash has a bond with his Pokemon, so if he lost, it'd be screwing over a 4 year old build up.
The post in spoilers is something that was revealed months ago (before Dawn vs Zoey was) that I'm surprised no one here has apparently seen.
Anyway, I truthfully am liking it's Barry vs Paul. I'd rather that and Nando vs Ash than any other combo. Nando didn't go against Dawn, I'm glad he's going against someone on the main characters.