Reuters unnamed source
The crux of the problems is that the ECB will soon struggle to by 80 billion euros per month of bonds because of restrictions on which countries and maturities it can buy along with limits on how much of each issue it can own.
So some kind of tweak is inevitable. They'll probably keep the country key but skew maturities or the lower limit of -0.10% or issue limits so they can continue. Expect some leaks about what that might be in the lead-up to the December ECB (everything leaks in Europe).
