It's perpetual consolidation in enterprise, nothing has changed about that in decades. Microsoft eats Github. Atlassian eats Slack (or some other company does). Maybe Atlassian is the next Oracle, or maybe Oracle or Salesforce or SAP or Microsoft eats Atlassian.
The one thing every scenario has in common: the little fish don't stick around and cooperate, they all get eaten and merged into ever larger companies. Nothing can stop that process, all the little fish have shareholders more than willing to sell when the big price comes in from the giants.
PeopleSoft, Siebel, Sun, MySQL, Great Plains, Sybase, Business Objects, Ariba, SuccessFactors, Concur, RightNow, Taleo, MuleSoft, Demandware, ExactTarget, etc etc
It's the same thing going on over and over again. The little fish never stick around. Box will end up in someone's stomach just the same as the rest.