Law /
Problems in Poland - Swiss mortgage, bankruptcy, jail, mental health etc [26]
The problem is that the banks tomorrow could exchange all CHF mortgages for PLN mortgages at current exchange rates. It's not an issue for the bank, but for the consumer. They would be converting at 3.89zl/1CHF and suddenly facing a rise in interest rates from somewhere around 1% to around 3-3.5%. They would be in even more pain as a result, and furthermore, they'd be subject to the PLN interest rate rising, which it will at some point. The CHF on the other hand will not see positive interest rates for years to come due to the sheer strength of the Franc. As far as I know, banks are quite willing to offer a conversion into PLN.
As for people defaulting, I think it's rather that the banks know that there's little to no chance of them finding buyers for repossessed properties. It's rather better to keep people paying something, particularly as people are unlikely to trash houses that they still have a prospect of owning in the future.
Unfortunately, with what you say, it's a common scenario in Poland. People were building huge houses way beyond their means, often taking CHF mortgages to get even more from the bank. These people were not poor people, but rather middle class people who had grown up under communism/hardships of the 90's and who wanted it all now.
The problem is that these houses are often very...hmm, tailored to their own specific taste. If it was built with the help of family, then it's quite possible that the construction is also not exactly top quality, which means that potential buyers will be few and far between. Most buyers would run a mile as soon as they discover that Uncle Pawel was actually doing the plumbing and Cousin Piotr that did the electricity, as it's likely that vodka and a good time was enjoyed.
I understand that you're pinning your hopes on the mortgages being annulled, but if anything, the only realistic prospect is for the mortgage to be compulsory revalued into PLN, or possibly the banks will be forced to peg the mortgage to the CHF at today's exchange rate. There's no way that mortgage holders will see the banks forced to peg it at 2.2 or whatever the rate was when they signed the contract, as it would put the banks in trouble.
If you don't mind me asking, in which part of Poland is the property?