Blockchain has the potential to be implemented in various industries. Use cases are still getting developed in niche sectors like Supply Chain, Medicine, Real Estate, etc. Once we somewhat figured out the technical foundations of a public blockchain ( Layer 1s, Relay Chains, Layer 2s, experimenting with Governance, trying different Tokenomics, etc), we were ready to build stacks over the foundational framework. Defi was the first sector that gained overwhelming popularity. This was soon followed by Non-Fungible Tokens. Since then Defi has gone back to development mode and it is said that NFTs have entered a bubble zone. These 2 sectors will come back in multiple waves bringing in the need for upgraded solutions (for example Uniswap v3, AAVE launching protocol for institutions). There are however newer sectors that will rise into prominence.