Google has awesome data center technology, and my guess is they have at least as many servers as AWS (even if most of those servers are for internal use). If they are willing to invest for the long term, they can be a credible player.
Microsoft appears to be deeply committed to Azure. As in - we can not lose, we will spend whatever it takes to make this fly. They will also leverage their somewhat captive enterprise customers with Azure / AD integration.
Not clear to me how the rest of the pack will fare.