Do you think they will somehow turn the corner or is Firefox inevitably going to die? I cannot see how they could possibly avoid it if they keep on doing what they currently are doing.
(As sad as it is but I wouldn't even put it past them to read one day that "sustaining a browser with a low digit marketshare is not a reasonable use of our resources anymore" and that "Mozilla is glad to announce that from now on, we rather focus on the broader mission instead").
So if we already have a working tool, why do we want to spend the redundant work to invent more tools that solves the same problem, or to maintain the other tools so they are all standard-compliant?
Of course, it's a different story if the existing tool is monopolized by a commercial company. But Chrome is open sourced, and there is a committee steering the future Web standards.
So imo we don't need another Chrome, just like we don't need another Linux.