the problem with that view, in my opinion, is that's a pointless balance. there's no reason for it.
Plus it never happens. For a short time there are two of each Jedi and Sith, but we can still extrapolate more Dark side users, and there really isn't anything to say specifically that there are NO other Jedi ANYWHERE. I mean, if those two escape, why not a few others? plus, at the end of Jedi, there are no Sith, and if you're counting Leia as one to make your numbers even, there are, briefly THREE Jedi (as Anakin forsakes the Dark Side).
Though I question whether you can call them "Jedi" in the traditional sense anyway. Sure, they're Jedi (the movie is called the RETURN of the Jedi, after all) but it's not like they've formed an order or are the same thing they were before. This specific argument isn't about nomenclature, it's about putting Jedi and Sith opposed to each other. That dichotomy doesn't exist at all by the end of Ep. 3. By the end of Ep 6, neither party exists, so I think it's pointless to say the point of the prophecy was to equalize the power or numbers of either.
At the end of the chronology presented in the 6 movies and the TV series we're given, there is only one Jedi. And one potential Jedi. And no Sith. And a lot of old guidence being given to the new Jedi. So neither power or numbers of even the inheritors of these factions is in balance. In fact, one could argue that neither order could be allowed to exist if there was to be a balance.
So, the question is, what would the destruction of those orders achieve? THe elimination of the Sith removes the organized teaching of fear and hatred as means to power. The destruction of the Jedi removes the institutionalized teaching of permanent abstinance and unnatural refrain from affection and social interaction. Overall "influence" rests still with those who wish to use the light side of the Force, so I have to conclude to my earlier position, that the "balance" spoken of in the prophecy is about balanced lives, emotionally and lifestyle-wise.