The scalability constraint is a fundamental one. A single cryptocurrency cannot scale beyond a certain TPS without sharding. But sharding reduces the decentralization of each shard. Also, rebalancing existing shards when adding new ones also introduces its own decentralization problems.
I think the way forward for acalability will be multi-chain. Each blockchain has its own accounts and own token but is connected to other chains via fully automated DEXs. The blockchains will form a hierarchy of chains with the most trusted and busiest one at the top. I think there will be a trend to make a consistent payment API so that any cryptocurrency can be used in the place of any other, online shops will use on-chain DEX trade price and volume data to determine which coins they accept and for what value.
I think the way forward for acalability will be multi-chain. Each blockchain has its own accounts and own token but is connected to other chains via fully automated DEXs. The blockchains will form a hierarchy of chains with the most trusted and busiest one at the top. I think there will be a trend to make a consistent payment API so that any cryptocurrency can be used in the place of any other, online shops will use on-chain DEX trade price and volume data to determine which coins they accept and for what value.