From my experience with ING (both with investment RSP and Tax-Free savings accounts), I would like to think that they are not pulling a lot of their income from an account like this new FREE account they have proposed. The fact that they are a completely virtual banking institution keeps their overhead low and allows for them to give higher interest rates to the people that bank with them.
This is just a speculation, but I think a lot of their profits come from their mortgages obviously generated from the interest.
Overall, I`ve had a great experience dealing with ING for savings services. Good interest rates (as far as "good" is concerned on rates for a savings account), but their customer service department stands out a head above the rest, including my own bank (won`t name names). I would recommend checking them out if you haven`t already.