Oh, wow. I had not realized that number was the DAILY signups...
revenue, not income - he's going to have high server costs now and if he wants to keep this scaling up, i suspect he'll need to bring on another person soon. at the very least, a customer service rep.
still should easily net him a nice recurring six figure salary.
Currently adding over 4k paid users per day.
He reaches $1 million at just over 40k paid users.
Factor in the userbase he's already been building for 4 years, the hundreds of thousands of Google Readers currently leaving, the millions that will need to find a replacement before July, and the last-minute movers on July 1st.
I don't think server costs and a couple of employees will put him below a 7 figure income.
The amount of annual income from this product will now end with "million".