They're not going to start making triple-typed Pokémon now, not unless they want to go back to all of the other should've-been-triple-types over the five generations and give them their proper typing. Of course then they'd also be forced to acknowledge that some of the single-types from those same evolutionary lines should've also had additional types. (Example: yeah, it's all well and good to go back and make Vibrava and Flygon Ground/Bug/Dragon, but then you're sort of forced to admit that Trapinch should've been Ground/Bug all along.) There are...a lot of Pokémon that seem like they shouldn't have the type combo that they have, and not just because of the two-type limit.
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I'm a cat person, but I can still appreciate a SuperNiceDog.