Yeah true. Though one way it could play out is that the existing behemoths transition from a centralized company structure to a decentralized algorithmic structure to save costs.
If the "boring" functions of big tech companies can be automated, at some point it makes sense to just spin that out into a Decentralized Autonomous Organization (DAO) aka smart contract/s on a platform like Ethereum. The company still receives the tiny transaction fee from that running contract, but they don't need any employees/infrastructure/costs so overall revenue wouldn't be affected from the change.
Consumer-facing nothing will have changed. Same apps, same beautiful interfaces. But 99% of the backend business operations will be performed by distributed, decentralized algorithms running on a blockchain.
Particularly as the sharing economy unicorns scale (Uber, Airbnb etc) they are essentially becoming the single interface and algorithm to entire industries. Uber will become the single monopolized UI to the entirety of all transport (people/food/parcels) with some other minor competitors.
But Uber can very easily be decentralized. And actually the bigger they get, the easier it will be to decentralize them as a third party (because the trained workforce and behaviour is established, and will gravitate on economics... lower prices, higher wages). And so hopefully the costs, competition, monopoly legal issues and scaling pressures (at 1B+ users) will encourage Uber itself to decentralize and run their entire operations transparently on a blockchain.
Maybe in some other capacity Google/Facebook/Apple/Microsoft/Amazon will follow suit. Though personally I'm looking forward to a world where sharing 24/7 video and audio feeds to the cloud for processing is seen as normal. Collecting all human input/output data is the first step in my opinion toward building a super AI around humanity. Google and Facebook's centralized nature is capturing the most data at the moment, so they're best positioned.
/2c