Thanks! Yes, the game will evolve, there will be a lot more cards and content in the future, and I'm also thinking about how to diversify the basic concept.
One more observation: I think the rebirth system can lead to problems. for example: if i get my first reset with 20 cards, my permanent luck increase will be lower than if i did it with 24 cards. But since the next reset is more expensive than the first one, players get punished for resetting as soon as they can. Players who reset "too early" get a "debuff" in comparison to other players who stayed longer to gain a few more cards, which makes it easier to get shards in the next reset. Maybe it would be more fair to have a fixed rebirth cost (1 million maybe?) and the luck bonuses get more extreme the more cards you find (e.g. 20 cards give +0,1 luck and 40 cards give +0,8 luck instead of +0,1 to make rebirths more attractive). This way numbers can always keep increasing (and rarity too!), more active gameplay get rewarded (more resets force more active gameplay at the start after each rebirth) and bad choices in the past dont affect the rest of the complete save file negatively.
I know its a long text, im sry.
Your idea is really interesting! But at the moment, I'm not focused on such a rapid increase in the number of rebirths, because I simply won't have enough time to create content for everything. I initially designed this system to be a bit unfair, haha. However, I might consider implementing your suggestion in the future.