A new report, stemming from a "high-ranking UK industry source, has explained that the consumer won't actually be the one paying the £35 activation fee for a used Xbox One game. Instead, the retailer will be paying the fee, so you will only be forced to pay whatever the retailer is selling it for. Although you can bet that a £35 fee -- which Microsoft is said to still be deciding on -- can result in some pretty pricey used games.
In essence, Microsoft will control the cost of used games because of this fee. If the activation fee -- which will go to both the publisher and Microsoft -- is too high, the retailer won't be able to offer the game for much cheaper. It's unclear if the fee will increase or decrease depending on time, but you can bet that pre-owned games will be a tad bit more expensive then they are now.
Sony's plans for pre-owned games have not fully been explained either, but the source doubts we'll see something similar on the PS4.