Public clouds are not a niche service and to say companies will never adopt nosql even as they improve every day is a very strong statement. Companies don't want to manage their databases; they just want uptime, performance and control (which in the past implies direct management), but this is exactly what MongoHQ is offering and why they will succeed.
Theyre all getting traction in certain niches, but 99 out of 100 companies are going to be very skeptical about using something like this and ill wager it will take years for that to change.
Looking at EC2 or a NoSQL solution in isolation maybe, but I know that if i suggested NoSQL database as a service to most of my customers for their production data I would be laughed out of the building.
