just a thought, I know is too late, but always might be interesting.
On many games (also on Oblivion) you could turn off blood in game settings. So going this way you could imagine that game can be bought in two versions: mature and teen.
When purchasing game someone could choose the version - same way as we put date of birth when entering ESO site. Even more when purchasing the decision could be more controlled so for example in country where it is forbidden to sell M-rated games to teens seller could simply choose right version.
In short game could be in two versions: ESO-M and ESO-T.
So when playing ESO-T:
- there could be very little blood
- no nudity
- gore could be simply made grey assuming it is some mud
- some textures could be "teened"
- spoken language could be also slightly modified - but it would be only in few small parts, some words could be simply cut off, so no big deal
Most of the above fixes are just in graphic.
Then just everybody would be happy - there would be one version for ESRB rating, that actually nobody buys - well may be then it would not make sense because there is no market loss coming from rating, but if there is loss, then someone could estimate how much and how much does it cost to prepare light version of ESO.