Definitely save your cubes. We have no firm proof about the next event though some new stuff in the code indicates it might be a equally sided event in terms of bosses (3 Autobots vs 3 'Cons). There will probably be some sort of announcement early the day it starts saying "Coming soon". That is what happened for this event. The less pessimistic side of me hopes that they'll give us a firm start date so I can know for sure, but I'm not counting on it.