Joel Steiner took some pretty awesome notes during the last GAE meetup. He has some concerns though about the future of GAE on the following fronts:

• Vendor lockin - “If you code to GAE, how can you break your app out of their system and run it on a competitors system if for some reason GAE’s terms, price or other features just aren’t cutting it for you.”
• Importing Ginormous amounts of data – “Since you pay per transaction, and for data transferred and stored, the thought of trying to import my 10 million record events database was a bit scary.”
• Refactoring your data – “So lets say you’ve gotten your 15 millions records happily into the Google datastore, but suddenly business requirements change and you need to significantly refactor the way your data is structured. Now, this is a hard situation in any database system, but the thought of only having external API access to do this amount of work is daunting.”