A fan in the dock may be a pretty good indication too that we could be looking at the option of a full clocked or very high clocked Tegra T239 in docked mode. Two fans and a fan at all in docked mode just seems very extreme unless you are planning to push the chip to max or near max and really use all of those 1536 CUDA cores.
That does then kind of ask the question about the handheld mode. Obviously a larger battery in a larger system is a given, but that still may not give you enough juice if they're going so hard on docked mode.
I wonder if we could see something like Joycon battery sharing with the main unit in handheld mode, because think about it, bigger Joycons should be able to accommodate themselves larger batteries too, that extra battery could theoretically be shared with the main unit, like two external battery packs. It would make an awful lot of sense for higher performance games.
The shape of the dock also seems interesting, now this is a different leak but it's been said that the new dock will be a curved to flat shape, kind of like the Burj Al Arab building in Dubai. Maybe this shape is better for cooling?:
