Vitalik Buterin assures that existing EVM-based smart contracts will remain fully functional and interoperable with new RISC-V-based contracts, preserving backward compatibility during Ethereum’s proposed transition.

Quotes that support claims

Buterin's proposal considers supporting both EVM and RISC-V contracts as well as creating a dedicated interpreter for converting EVM contracts into a RISC-V equivalent.

Old-style EVM contracts will continue to work and will be fully two-way interoperable with new-style RISC-V contracts.