Saw this rumor on Screamscape that Dragon Challenge might be the next coaster to get a big refurbishment, albeit not quite as extensive as Hulk's. I assume by new trains that they mean Banshee-style trains. I certainly hope that a refurbishment might allow the two sides to duel again. When I rode it a few years ago, the dueling factor was something that really made it special.
2017-2018 - Dragon Challenge Refurbishment - Rumor - (11/24/15) I've been told that once the rebuild of The Incredible Hulk coaster is complete, we can expect to see a large refurbishment performed on the Dragon's Challenge coasters as well,
though it isn't expected to be as extreme as the Hulk's. According to one source, we will be all new coaster trains brought in, but we can expect to see the existing track get refurbished (though some sections may need replacing) as well as a complete repaint of the entire attraction.
So far the timeframe hasn't been locked down, but they expected it to take place sometime within the two years following the completion of the Hulk rebuild, which would mean sometime between mid 2016 to mid-2018. As always, there is always the constant rumor that Universal just might allow the dragon's to "duel" once again... but no one can confirm if this will happen for sure.