I've thought also about this topic sometimes. Crypto market cap has potential at least (midterm) to reach 10% of total market cap (including classic exchanges). You're values are right. Classic exchanges are around 70 trillion, and cryptos only 0.1 trillion. 10% would be 7 trillion, so growth is x70.

I'm confident this could happen sometime before 2025 (2022, 2023 maybe...)

Best case, and long term, could be crypto having about 30 - 60% of total market cap, but for this we would need at least 30 years from now. Could be useful for retirement anyway