They won't split up a company, they'll outsource the labor. They will still get the profitable output from the worker, but at a difference price. Those bigger companies may also decide not to operate in Switzerland.
I also disagree about small businesses not being affected. Let's say the lowest paid worker makes $10 an hour. I don't know the average wage in Switzerland, but let's just go with it. That's $20,800 a year. That means the CEO can only make $249,600. That will affect many businesses, not just big companies. There's many ways to get money out of a business, so CEOs will still get paid.
And I completely disagree about common success. The business owner makes the risk to start the business. Employees trade their time for money. Some owners may be generous and reward employees with equity, but that's optional. That whole "you didn't build that" line is a load of crap.