What ever type we get will most likely be known in Japan and in English by the same thing or if Japanese is different, then the English will translate to the same thing. So what ever Japanese is for Light will be Light if Light appears. Same for Fairy.
Xander's right, most types that have different names between the Japanese and English versions usually have the same meaning, although some people didn't easily catch the "Evil" type becoming Dark and they thought it represented actual darkness but the type itself is actually based around tricks and playing dirty, not to mention there are 3 Dark-type Pokemon families based on criminal stereotypes.
Fairy and Light would definitely not have the same meaning as stated above. I mean, like what Xander stated there, the Fairy egg group kept its Japanese name in the English versions so if Fairy was a type, it would probably be the same.
That would seem a bit complex imo, basing teams around stats or certain circumstances might be interesting but it's pretty hard to work out. I always preferred the traditional type specialty since we've had it since the early days of Pokemon.