Continuing to acquire and/or drive out of business other players before that happens so that there aren't sufficient competitive opportunities to drive your costs up to unacceptable levels. (It helps if as well as approaching a labor monopsony you are also becoming a monopoly on the services sold from that labor so that you can use the monopoly rents to offset any labor cost increases you don't manage to forestall by destroying other opportunities.)
For example, Google, the "be evil" toxic advertising-tracking company, is now a splintered subsidiary of Alphabet.
But Amazon and Facebook don't seem much interested in doing the subsidiary thing, at least not to Alphabet scale, so I'm not sure what they'll do instead.