I'm not sure what you mean by, "it just pushes the problem down into the filesystem". Could you explain?
On the upside, SQLite will take disk space, memory, and CPU proportional to actual usage, and compared to (say) Ruby or Python, it's a drop in the bucket.
As to the discontinuous transition between it and a bigger system, sure. It's a trade-off. So is worrying about scalability plans during early prototyping, though.
If you're building a multitenant distributed system like GAE, the SQLite blob needs to be stored in a distributed system too, even if you don't need to handle concurrent access.
Got it. SQLite also explicitly notes that its locking does not work properly with many broken implementations of NFS (http://sqlite.org/faq.html#q5), so that's not an option.
On the upside, SQLite will take disk space, memory, and CPU proportional to actual usage, and compared to (say) Ruby or Python, it's a drop in the bucket.
As to the discontinuous transition between it and a bigger system, sure. It's a trade-off. So is worrying about scalability plans during early prototyping, though.