Difficult to say how much is already priced in. Remember all the FOMO about bitcoin halving, but everyone knew it would happen, and it was factored in well ahead of time. Likely we will see the same with ETH 2.0. The only thing that complicates matters is that we don't know how much of the current rise is due to anticipation of 2.0, and how much is DeFi.
But whether or not we see an immediate rise for ETH after 2.0 goes live, the future does look very strong for Ethereum.