Im not sure if bitcoin is ready for mainstream. Default client is certainly not.
Default client (Satoshi client) will never be ready for mainstream if it includes a full blockchain download. I predict that if Bitcoin ever goes mainstream it will be through some cloud wallet service like coinbase.com. Then, the only clients that might go mainstream will be 'light' clients like Electrum. People's attention spans these days are extremely short. A relatively few number of people will want to sit and wait for the blockchain to download.