In my opinion, it is a common misconception to assume that excess usage = centralization and later, a ban. This is not directly true.
Rather, usage shows that a Pokemon is powerful, and THAT's what sparks a consideration for ban or a stage for centralization. We don't ban Pokemon because they're used too much; we ban them because they're powerful and affect the meta in negative ways, and those traits are displayed by the warning signs of high usage. But as people have stated before, high usage does not always equal power and centralization, as Scizor is a prime example of something that is used a heckuvalot but really isn't overpowered or centralizing, so to speak.
Also, vice versa. Just because Pokemon are unpopular doesn't mean that they aren't banworthy and will not have any undesirable effects on the OU meta. I mean, we have suspected and almost banned many relatively not overpopular Pokemon, such as Keldeo, who is used in about 10% of teams, and even Volcarona in the beginning of BW1, which is now used in about 10% of teams as well. There are many things that affect usage other than power and centralization, including playability, synergy, and general matchups with the meta. Usage does not directly relate to power, nor vice versa.
But, for the sake of discussion, we should refer to centralization as our measure for power and whether or not something would negatively affect the meta, as opposed to usage, as some people are unfortunately doing. Actually, I wouldn't say we should completely throw away usage stats, but instead, a great way to measure a Pokemon's effect on the meta is to check the usage of other Pokemon that are severely affected by said measured Poke. Powerful and centralizing Pokemon will have a greater effect on the usage of other Pokemon than on the usage of themselves. Genesect was a great example of this (mainly because it was so blatantly broken, but ah, that's my own opinion there.). During Genesect's reign, Heatran was extremely popular, not only because it was the most solid counter to Genesect but also a solid teammate too. Fire-types and Sun in general also experienced more usage, brought into the spotlight because of their ability to check Genesect with their fast Fire attacks. Psychic-types such as Alakazam, Celebi, and Lati@s experienced a drop in usage because they were easily picked off by a Pokemon that was used in more teams than Scizor is today. We know this because in the months after Genesect was banned Psychic-types slowly rose in usage and Sun / Heatran dipped after losing a major 'job'. As you can tell by the usage stats of
other Pokemon, Genesect had a profound impact on the metagame and was very centralizing.
Connecting this back to the OP, I think the OU metagame would be truly 'ruined' if there exists a very stark and noticeable contrast in usage between a select few centralizing Pokemon and basically the rest of the metagame. Unfortunately, the BW2 LC metagame was a very good example of this problem, as it was heavily centralized around Murkrow, Misdreavus, and Mienfoo. (still, LC is terrific and has high hopes for Gen 6, so ofc we didn't give up on it) All three had about 30-40% usage, while the rest of the viable metagame hovered at around 10-20% usage. The problem is more so that the three had so much more usage than the rest of the meta as opposed to the fact that their usage itself was so high. Even if we had a meta where around 20 or so Pokemon were at 30% usage, we wouldn't really have any problems with overcentralization because we have 20 goddamn Pokemon to work with. However, things start to get bad when only a few split from the group and achieve much higher levels of activity, creating a negative stark contrast with the rest of the meta. Something like this would most likely happen when one or a few Pokemon are so absurdly more powerful than the rest of the meta that all other Pokemon are deemed useless and only a select few that are useful in countering or aiding said Pokemon remain viable. (this was basically the problem in LC :/) Thankfully, in OU, we have bans, and the lovely Uber tier to help us out of those kinds of situations.
So, in conclusion, I feel that the OU tier would only ever 'fail' if we had a few Pokemon with drastically higher usage than the rest of the metagame, caused by the fact that they are so powerful that using any other Pokemon would just be a waste. We've never achieved that, thankfully, but we have come close at times (*cough* Genesect *cough*). Thankfully, the relative similarity in power and usefulness amongst the current OU meta means that really the only way to break the OU tier in such a way would be to unleash an Uber God amongst the people, which nobody in their right mind would do.
FREE ARCEUS
FREE HO-OH
