From what I've read it will be a reverse clicky, which makes for a great mode selector. Full press to turn on, each half press to switch to next mode, full press at any time to turn off.
I would also imagine that it will be a reverse clickie. Pros and cons either way. As LowBat said, reverse clickie makes mode selection easier. However, it eliminates momentary on unless you click it on and use it as a twistie.