Seems like it may be the case, and with a theme that's been speculated about for a while to boot. The reason why it suddenly looks like it might become a thing is because PokéExperto said so, even adding it to their type chart. If that name doesn't ring a bell... this is the same fansite that leaked copious amounts of classified information prior to BW1's release.
Paradoxically, this is the very reason why I'm taking this news with a grain of salt. After all, is Gamefreak stupid enough to let them anywhere near top secret info after they just threw every NDA they signed into a fire last time around? Any sensible company would answer any of their demands with a well-deserved "fuck you". Does Gamefreak belong to that category?
Then there's the obvious matter of introducing a new type so late into the series' lifespan meaning said type won't be really effective for the next decade due to underpopulation, mass retcons or not (edit: mass retcons might make it catch up or even surpass the least common types, actually). (And to add to that, most of these retcons would be applied to Pokémon that are currently mono-Normal. Hello lack of typing variety!)
So amazingly, the masses of drooling idiots who couldn't put a non-Fire move on their Charizard to save their lives could actually be bang on, if this turns out to be true. And considering who this is coming from... I wouldn't say it's anywhere close to confirmed due to their previous NDA breach antics, but it's worth keeping an eye on.