MetaMask described the Solana integration as the first step in a multichain expansion strategy aimed at supporting non-EVM networks and consolidating blockchain access

Quotes that support claims

Solana is just the start. We’ll be adding more non-EVM networks over the coming months, to make wallet juggling a thing of the past. One wallet, one interface, every network,” MetaMask.

MetaMask has announced plans to soon add other non-EVM (Ethereum Virtual Machine) networks, further expanding the range of possibilities offered to users.