Part of the reason for the Panama Canal cruises is to reposition ships. As PP noted that used to be westbound in the spring and eastbound in the fall to get a ship on the West Coast/Alaska for the summer. As
DCL continues to increase its fleet, there may be less need to reposition ships, as each ship could theoretically have its own 'area' instead of one ship having to cover multiple. That's an oversimplification, yes, but helps to make the point.
All that to say, DCL may not
need to do Panama Canal cruises in the future to reposition ships (or may not need to as often). As another PP noted, we've seen that this year since the Wonder is going to Australia instead of coming back to te canal to the East Coast after summer season. Doesn't mean DCL won't still do Panama Canal cruises as they are popular, they just might not be as frequent.
That's all my speculation based on the logic that Panama Canal cruises are technically repositioning cruises. No one knows for sure what DCL will do.
(I've also heard rumors that the Fantasy may do a Panama Canal cruise at some point when the Treasure [allegedly] takes over her itineraries out of Port Canaveral. If the Fantasy every does do a canal cruise I will do whatever I can to be on it, lol.)