The Polkadot blockchain aims to provide interoperability and security to other blockchains, helping to solve issues like scalability.
In a multi-blockchain world, interoperability could be a potentially valuable function. If a small number of blockchains becomes dominant this value proposition will be significantly weakened though.
Polkadot is currently the leading interoperability blockchain, but its value is uncertain and dependent on how the blockchain ecosystem evolves in the future.
SOURCE: Richard Durant, Polkadot: Networking For Blockchains, Mar. 08, 2021 11:38 PM ET, SeekingAlpha
Polkadot: Can DOT 10x in 2021?? DEEP DIVE!! (Video)
SOURCE : COIN BUREAU, Jan 12, 2021, YouTube