Stallman on GCC, LLVM, and copyleft

But I think any developer - asked by his employer to maintain a private branch - is likely to kick back hard (if not that successfully).

Because one of two things is almost inevitable ... either

(1) the private fork will rapidly stagnate, or
(2) 90% of the developer's work will be make-work, trying to keep up with the Free version, for which the employer will be reluctant to pay.

In either scenario, I don't think the Free version has much to worry about. In scenario 1, the private branch won't be competitive. In scenario 2, the employer will have difficulty retaining staff.

Cheers,
Wol