There are a couple of problems with your theory, though it could play out that way. Right now the smaller vendors are often more efficient than the larger ones. Smaller players can be more nimble.
Second the larger players all have vastly different models. Just to pick a few examples of the bigger players
AWS -- Generic low quality server experience offered cheaply. Walmart
Sungard -- Highly custom environments quality management lots of value added labor
Verizon (was Terremark) -- Moderately custom environments, mix of high performance cloud IaaS and colo. Some value added services with strong partner service model.
Oracle -- Unified cloud stack offering IaaS plus advanced management especially knowledge of Oracle applications
Azure -- IaaS with Microsoft based PaaS. Good pricing on SQL Server.
How do those consolidate? I think we are looking at a situation more like clothing where stores are genuinely different fulfilling niches for various customers.