Even if you don't sign a CLA, can't someone take an Apache/BSD/MIT-licensed work and make a closed source form of it? The license effectively just requires the

Even if you don't sign a CLA, can't someone take an Apache/BSD/MIT-licensed work and make a closed source form of it? The license effectively just requires them to mention where the code came from. Whether you signed a CLA or not seems pretty irrelevant. Apache says for example: "You may add Your own copyright statement to Your modifications and may provide additional or different license terms and conditions for use, reproduction, or distribution of Your modifications, or for any such Derivative Works as a whole [...]". I think the OP's concern only applies to GPL software, which in my experience is pretty rare at this point.