Yes, it is possible to mint crvUSD while providing Crv LP tokens as collateral. According to a tweet from the IPOR Intern, the initial collateral for crvUSD will be ETH, but there may be more added later. This means that Crv LP tokens could be used as collateral for crvUSD in the future. As of now, there is no official information on when or if this will be possible, but it is something to keep an eye on in the future.