I have heard that there might be, but the best way to find out is through your SE rather than TAC. Your SE should either have or be able to obtain information on product support information for the future. And if it is not on the roadmap right now, you can do an enhancement request to have the Firefox support for the Mac.
How are your users accessing the iNotes server? I have seen some people resolve your conundrum by having users sign in to the IVE using Safari, launch JSAM or Network Connect, and then connect to iNotes (or the needed application) with Firefox. I don't know what your requirements for services are, but that may be an option.