Nicu – the question is, who would you rather have as an ally? Mozilla, or Apple? I know which one I’d pick – the people who open-sourced the browser and have been maintaining the very good Firefox experience for Linux (even if there are details to fill in), not the company making a proprietary platform that competes with ours for desktop marketshare.
That said, there is actually work ongoing now to integrate Tango for example. I don’t think it’s going to be easier or make more sense to change rendering engines just for the remaining integration points that could have been done as a Mozilla patch instead.