As an ex-Mozilla fan user (I still use it, but for legacy sites/plugins which doesn't work in Vivaldi).
But I really hope they manage to fix the UI (no australis, please, make it "yours"), the resource usage (tab-hogging with newer firefox is almost impossible XD), plugins and extensions area (ok for PPAPI support, but they'll still lose users which use it for its NPAPI support - and even that are planning to drop).
We'll see

You can (maybe) do it =D
I was less fan - starting about 2 version which was way slower than previous mozilla products; well I don't like chrome too (too "exposed", too minimal, too.. chrome)
I don't think Mozilla will ever fork chromium, as it's like to trash all the work to firefox core - the Gecko.
But yes, should be heavily improved, even delaying new browser releases.