This just keeps making the Drake equation either a) more confusing, or b) more wrong in terms of its premises.
Once we did the fly by of Pluto, I was pretty much convinced that just about every spot capable of harboring carbon based life probably does. I'm of the mind that these large icy bodies orbiting at a distance sufficient for their to be enough of an ice cycle to have an annual freeze thaw event are probably sufficient for the development of proto-life compounds. Nitrates, nitrites, ammonia, maybe some larger carbon volatiles. Smack one into a large enough planet and you get a healthy enough dose of the chemistry it might allow for so interesting things to start happening. It doesn't have to happen this way however. Plenty of other interesting ways abiogenesis can happen..
Which again, makes the Dake equation even more confusing, or alternatively, entirely the wrong way to be asking the question.