Unlikely. Walled gardens already use their own search so what does Google care if they change the technology behind it. They've also made the conscious decision

Unlikely. Walled gardens already use their own search so what does Google care if they change the technology behind it. They've also made the conscious decision to be walled gardens so I don't see a federation play. Also, distributed search = incredibly slow search. Having to reach out to dozens or hundreds of backends for each query creates all kinds of problems (latency, reliability). So that leaves us back at each walled garden needing to index web content in order to offer it alongside their own results. Large scale indexing is something Google definitely has a significant lead in, which would take many years to overcome.