So there is a real scalability problem?
Yes there is a real scalability problem if all users are full clients. No, that was never the intention. We are already way past the point (imho) that we need more full clients. We need more light clients and overlay networks to support them, such as BitcoinSpinner, Electrum & Stratum.
I say a scalability problem may not exist.
The fact is transactions on the core Bitcoin network are NOT ideal. Such transactions are slow to confirm, and are not user friendly for more mainstream use.
What makes far more sense is eWallet/PayPal-esque transactions. Pay or receive amounts to/from anyone with an email address. The transaction is instant, and the experience as user-friendly as you like.
The majority of Bitcoin transactions should be rows updated in databases of such services. Typical transactions are not going to be large, so such services don't need to act as banks and store big Bitcoin balances. They are instead streamlined to be transactional. I estimate 70% of all Bitcoin transactions could and would be better serviced this way.
People can still store the majority of their coins offline, or however they like, and deposit/withdraw from the eWallets (infrequently) as necessary.