The current 1 year treasury yield is 2%. Assuming the deal closes one year from now, and the deal is guaranteed to pass (meaning the treasury rate is the appropriate discount rate) the stock price today should be $93.
The QQQ has declined 15% since the deal was announced. Assuming this is the correct ratio for Activision (probably a bit optimistic) the stock price today would be $55.
With the current price of $76.39, that suggests a 56% chance of the deal going through. A bit more pessimistic than Hoeg.