I honestly don't see why, in that amount of certain, they need a new singer. Hell, they are five talented guys. Plus, Mike is a genius. They could put out something very easily, making the crowd sing some of the well-known Chester's parts (In The End, Faint, hell... even One Step Closer could work out).
There's a future for the band. For Linkin Park. Let them take whatever time they think it is necessary to clear up their minds as much as possible and, when the time comes, I'm sure the fanbase will be there supporting the decision they take.