There seems to be some confusion on the web regarding a 5 year contract (from 2014) that Pirelli wants with F1. Apparently Ecclestone was asked about it last weekend and denied reports that it was signed and sealed. Other sources are saying that it is Pirelli holding out because they want to be able to supply the "right" tyres.
The truth as ever lies somewhere in between. I suspect that Pirelli are at last becoming concerned about being asked to provide lower quality performance products than they are capable of making. Pirelli's concern will be that Joe and Jane Ordinary Public don't necessarily understand the demands being made of them in F1 and that the public image of their road tyres is, or may be, tarnished by association.