The question is: can that income fund the Google-style salaries and benefits that are currently being payed for people working on it?

Otherwise lots of existing employees may not want to be part of this split company. If that is a large loss of talent (think veterans with lots of experience) that could hurt the quality (security, stability) and velocity of the project resulting in much less interest from those companies to pay the Chrome company for their services. What I'd suspect at that point is that Google might just fork it and develop it internally for internal use only (it's going to be hard to trust a third party browser to access internal confidential/critical resources when said third party has trouble maintaining high quality engineering talent). We're talking about state actors here that could have much easier time attacking a smaller Chrome company to introduce data exfiltration code.

Microsoft will probably have much of the high-quality engineering talent upstreaming work from Edge. Maybe Google will fork it, but nation-state actors haven't compromised Firefox (to our knowledge) even at its peak, why would they have more luck with Chrome?