I don't think it is going to happen. You don't have to rent a real office or hire an employee to run the business even if you really live in UAE.Substance means real activity in Freezone. Real offices, real employees.
FZs issues freelance(sole-trader) licenses, which means you can't hire an employee. Another example is SHAMS FZ in Sharjah. They only have flexi desk options because they don't have real office spaces, so you can't have real office space.
I expect less strict rules and more importance of individual tax certificates. I also expect all sole businesses like freelance permits or mainland sole proprietorship companies will be exempted from corporate tax because they're not corporate. They should be taxed under income tax which remans 0%.
Update: It looks like mainland sole proprietorship and even Freezone-based freelance licenses are subject to CT. Still waiting for detailed information but this makes freelance licenses useless.