There have been quite a few games in the Humble Bundle that are commercial failures, having sold thousands of copies on Steam, etc. instead of millions. In those cases the Humble Bundle is often the biggest revenue source for those developers, enough to fund the creation of new games.
Thousands of copies is not necessarily a commercial failure. We sold "just" 45k copies on Steam, which was enough for our 4 man team, before we went to Humble Bundle. When it comes to indie development, commercial success just means making enough to make the next game, which can be a surprisingly low amount if the costs of living are low.
I'd consider 45K a success in your case. By thousands I meant single digit thousands (in the 1K-5K range), not tens or hundreds of thousands. For some teams or individual creators with very low costs of living that's enough to sustain development, but at that point we're talking about living on less than minimum wage...
