I'm glad you brought this up! I can tell you that Season 1 will be ending with the release of Game Update 2.7. We are currently working on a blog for you all that will outline all the other information about the end of the season, including the rewards (and none of them are fireworks ). Look for this to be up by the end of the month.
That's all I can share currently, but if I get anything else, I will make sure to post it for you.
Thanks for updating us, should be interesting to see what kinda rewards are given!