If you fear being trapped sharecropping on Google's land -- that they might arbitrarily change the GAE rules, or prices, or capabilities, or even cancel the service entirely -- this gives you the possibility to migrate elsewhere.
Migrating elsewhere might not be better along any single dimension (price, speed, reliability, etc.) at any particular point in time. You might never need to do it. But having the option is gigantic. It makes GAE a much, much, safer platform on which to develop. In a pinch, you could port elsewhere in short order without reengineering your service architecture.
This is a very impressive move by Google. It removes my number one fear of using GAE. I'll be watching AppScale closely.
Google has killed a bunch of unprofitable projects recently. Lively died with 6 weeks' warning, and users who wanted to save their 3D handiwork were told to do so by "taking videos and screenshots of your rooms". I don't blame Google -- they don't owe anyone continued development of a money-losing business line -- but it happens.
And that's with Google still making barrels of money and not yet facing significant antitrust action for using profits from search to underprice products in other markets (like cloud services). With a few unprofitable quarters or lawsuits, what's the guarantee GAE will continue in an attractive form indefinitely? What if they decide they have to maximize revenue from developers locked-into the GAE platform? (Or what if the core team leaves to do their own startup?)
Even a tiny risk that another company could yank your platform out from under you on short notice, for arbitrary reasons having to do with their business needs (and not yours), may be unacceptable. AppScale mitigates that risk -- a lot.
Migrating elsewhere might not be better along any single dimension (price, speed, reliability, etc.) at any particular point in time. You might never need to do it. But having the option is gigantic. It makes GAE a much, much, safer platform on which to develop. In a pinch, you could port elsewhere in short order without reengineering your service architecture.
This is a very impressive move by Google. It removes my number one fear of using GAE. I'll be watching AppScale closely.