The Constant Product Market Maker Model will not be used in Uniswap v3, which makes completely fungible liquidity tokens impossible. Instead, Uniswap v3 moves to ‘Non-Fungible Liquidity’ and removes Native Liquidity Tokens to replace them with Liquidity Positions as individual NFT’s.
Since LP positions in v3 contain many more custom inputs such as Concentrated Liquidity, Range Orders, and Flexible Fees, all variables need to be contained within the individual non-fungible token (NFT).
Furthermore, Uniswap explains that they expect strategies will end up being tokenized,
"Over time we expect increasingly sophisticated strategies to be tokenized, making it possible for LPs to participate while maintaining a passive user experience. This could include multi-positions, auto-rebalancing to concentrate around the market price, fee reinvestment, lending, and more."
And that in order to provide these features to v3 LP’s, specific NFT periphery contracts need to be wrapped around the LP NFT,
"Anyone could create a periphery contract that wraps an individual liquidity position (including collected fees) in an ERC-721 non-fungible token."
Visor intends to build such a periphery, allowing Visor NFT vaults to wrap individual LP NFT’s.