One problem with that strategy is it forces you to use a licence with some sort of restriction (like copyleft) to make dual-licensing useful. You can of course

One problem with that strategy is it forces you to use a licence with some sort of restriction (like copyleft) to make dual-licensing useful. You can of course dual-license a BSD or MIT licensed project but no one would use the "dual" part of the dual-license since the copyfree license allows them to do everything they need. If you do this, the problem with dual-licensing a copyleft project is as follows: -The copyleft license allows use in other projects with the same copyleft license -The "dual" part allows use in proprietary licensed project (the stated enemy of the copyleft license) -The ones left out are projects that use other copyleft licenses and copyfree licenses. In my opinion dual-licensing copyleft licensed projects is a mockery of the purpose of copyleft. All this is however irrelevant to the discussion about funding core FLOSS software. It doesn't matter the license, the challenges to funding such a project are the same.