This is precisely the problem we're working on with Matrix.org - providing a standard API that can be used to bridge together all of these different protocols in one decentralised model. It's better than Trillian in that the defragmentation happens serverside and you can use any compatible client with it (or one of the existing services if you prefer). For instance, we turned on our first Matrix<->Slack bridge this week - see https://github.com/matrix-org/matrix-appservice-bridge/blob/... for how easy it was.