This is unlikely to happen. This topic has been brought up many times (either re-releasing event dragons, re-releasing stones, or allowing the use of stones on other event dragons) and it always ends the same way. The point is that the seasonal event dragons are one-time only and will not be released again. Not everyone will complete every dragon, and not everyone is even going to complete a single dragon. But the next season they’ll be higher level with better dragons and they’ll be more capable of getting farther.
The way the system is built is that with effort and little to no expense, the average player will finish one tier only. Those who spend or have been saving rubies might get two of the tiers. Only those that spend a lot and have the ability to place high on all events in the highest tiers will get enough to get all of the dragons and all their stones.