The GPL does not allow you to put further restrictions on the redistribution of sources. The termination of your business relationship can be argued to be a restriction. It's not settled.
> The termination of your business relationship can be argued to be a restriction.
It's not a very good argument. The GPL does not state nor does it imply a continuing duty to deliver you source code. You have a right to the source which corresponds to the binary you've been delivered. Period.
If I release a new binary to which I hold full copyright, after having delivered GPL sources to you, and I wish to change the license of that software to fully proprietary, your rights are not restricted re: the GPL bits you've previously received. Why? Because you should still have the source to the binary you received from me that was licensed as GPL.
It's not a very good argument. The GPL does not state nor does it imply a continuing duty to deliver you source code. You have a right to the source which corresponds to the binary you've been delivered. Period.
If I release a new binary to which I hold full copyright, after having delivered GPL sources to you, and I wish to change the license of that software to fully proprietary, your rights are not restricted re: the GPL bits you've previously received. Why? Because you should still have the source to the binary you received from me that was licensed as GPL.