Your description of Google Cloud as Mainframe perhaps better stated 'Service Bureau' is very accurate. My only question is why not call iCloude what it is 'Client Serving Computing'

Both approaches have there pros and cons but the one that best delivered Availability, Security, Data Protection is the mainframe/Google model. The procedures required to deliver have already been implemented unlike the 'Client serving model' that ended up producing to much complexity and data that could not be trusted. While it always comes down to the network basically both models have the same problem except for playing music or watching a movie. You can't do a payroll or banking transaction without a network.

With that said I am betting on Google Cloud. The reason being 'client Server' Didn't work and that is why Google exist. Even Microsoft will confirm it.