according to the kickstarter, a dual extruder is planned:
“The laser engraving module is only the beginning. Many other modules are under development, including a dual extruder, a ceramics extruder, and a pastry extruder (for chocolate, jam, and many other edibles).”
For triple or quadruple, wouldn’t be easier to think of a way to automatically swap the filament instead of having more and more extruder.
One of the problem is definitively the weight and size of printing head.
For the dual extruder, I would love to have head that use the tilting technology.
It is very simple, the extruder in use has a different angle as the other one; this allows to print without having the second extruder to touch/damaged the printed item.
This technology is already usued by Spiderbot.
I don’t know if there is a patent limitation for using the same system but it could also be done with a vertical adjustement of the extruder (printing one is few milimeters under the inactive one, and vice-versa when using the second extruder).