The end of life problem can be solved by source code escrow, with a clause putting the code under an open source license and published in case of the demise of the owning cpmpany.

With O'Sassy specifically, the end of life problem solves itself. If the original vendor stops offering the software, a third party offering the software is not competing with the original vendor. Thus, the third party can offer paid hosting for the software if the original vendor does not.

Or am I reading it wrong? I am not a lawyer.

If the company is sold for its assets is the code released to the public? Or removed from escrow and kept private?