I don't know how many of you remember a game called Maplestory, but in that game when you paid real world currency for cosmetics, you didn't actually get to keep them. Instead, you'd unlock them for 90 days, at which point they'd expire and you'd have to pay to unlock them again. This is a brilliant feature introduced by gaming company Nexon.
Now, don't get me wrong, Tencent is a pretty good game company, but they're nowhere near as innovative as Nexon. Imagine if instead of buying champions with blue essence, you could only buy Random Champion Packs which contain 3 random champion shards (90% for 450 champs, maybe like .01% for 6300). The only way to buy specific champs would be with real money.
With these extra resources, Tencent could afford to make more rentable skins for Akali, and others. They could release new champions with 7-8 passives instead of only 4-5, meaning players would have to spend more to keep up with the new overloaded champs, thus repeating the cycle. I know there are hundreds of useless posts about improving game balance, matchmaking, client performance, whatever, but this is a post I think Tencent can actually get behind.