Much more financial instability and the pressures continue to lead to cracks opening in the financial system. We all know that the Euro is somewhat artificial and that much of the economics and economies that support it are opaque and probably have much larger deficits than are reported. So, although the UK has a huge and growing cumulative deficit, it is a standalone deficit, economy and currency and as such the economy is (relatively !) easier to analyse.
So, I’m sure the clever Swiss bankers and government weighed up the risk / reward of keeping the cap. Given the likely QE and increasing European deficit I imagine they felt that supporting a weakening situation, which is likely to be long term, with the added possibly of further fracturing meant that continuing the cap was just going to be too expensive in terms of spend of their own currency reserves.
So this can only add to pressure on the Euro and Eurozone and in turn influence further instability.
And as a consequence the stand alone position of the UK is again amplified and appreciated as a relatively better safe haven.
So in summary the Swiss move is a positive factor for London property.