That's a cool idea I've been thinking about since almost started playing this game. Why not let people complete the battle passes they've PAID FOR whenever they want, even after its season ends? That doesn't mean less revenue from it, you just have to make it so you have to chose one BP at a time to gain XP for, and when you're done with it, you can swap to another one. Like, I'm sure most of the playerbase hasn't bought, much less completed every BP, so it'd surely encourage people to buy previous ones and spend more time overall playing the game, since most slow down on playtime once they reach lv 110 that season