Not much. They are moving from a regime where owner-occupier mortgage interest is deductible but you have to pay income tax on the imputed rental value of your owner-occupied home, to one where you don't pay the tax but also can't take the deduction.
For most Swiss people, who rent, it doesn't directly affect them. And even for most owner-occupiers, they never pay off their mortgages, and so the two effects currently cancel out. It's mostly a handout to rich people who can pay off a house (or inherited one).
Destroys it. The change will immediately raise property prices 5-10%. The only beneficiaries are those who own property today. It becomes harder to buy property, while people who own property free and clear get a huge tax benefit and only lose a tax deduction they weren't using. Essentially, it is generational warfare in the style of Prop. 13 in California.
The price of houses has just gone up because they have removed a real estate tax. Simple, and short sighted. The taxes need to be raised from somewhere so now let's see what convoluted and complex schemes they come up with to do that.
For most Swiss people, who rent, it doesn't directly affect them. And even for most owner-occupiers, they never pay off their mortgages, and so the two effects currently cancel out. It's mostly a handout to rich people who can pay off a house (or inherited one).