I agree, they will replace you as soon as they find the right person. I tried to negotiate a 1 year severance package with guaranteed bonus should that occur and they hesitated. I told them I knew they would be letting me go as soon as possible, and they tried to say they were shocked that I would even say such a thing, In reality, I spoke with someone after I left and they were already looking for my replacement, and just wanted me there to bring him up to speed.
Go now and enjoy the new start.