Central bankers may be trapped in a "QE-forever cycle", according to Bill Gross's latest musings, a warning that comes as European Central Bank president Mario Draghi raises the possibility of further asset purchases.

In his latest Investment Outlook, published on February 6, Gross argues that "in order to control volatility, and keep a floor under asset prices, central bankers may be trapped in a QE-forever cycle... withdrawal of stimulus, as has happened with the Fed in the past few years, seemingly must be replaced by an increased flow of asset purchases (bonds and stocks) from other central banks."