Great article!

I think the tool that will enable mass adoption will be an open source hardware wallet with the security of an offline Armory wallet and the ease-of-use of a smart phone.  It will be connected to exchanges for converting from or to fiat.  It will interface easily to wallets owned by merchants or other individuals for making and receiving payments.  It will handle escrow and multi-signature simply and easily.

It will be a safe place to store large sums of money, because a thief who steals it will have zero chance of getting a single satoshi out if it, yet you'll be able to recover everything from the one-time paper backup in your safe deposit box or multi-part backup distributed to your most-trusted friends and family.

The bulk of individuals and businesses are not going to adopt Bitcoin if it means their funds are vulnerable to thieves hacking in and stealing their money.  We need to develop the technology to keep bitcoins secure.  I think it needs to be on a device more secure from malware than a PC or smartphone.  And it needs open source hardware and software to drive innovation.

Oh, and by the way, we need to have it before Bitcoin loses its momentum.