Suppose one company buys another company outright. Should that company keep its customer list (effectively transferring it to the new owner), or throw it away, ditch all its customers, and start from square 1? Would you be happy as a customer if you were told that because your cellphone company had been bought, your contract is cancelled and they can't offer you another one, you have to go to the store and start over? Would you be happy as an employee of this company being bought?

Now, suppose the purchasing company isn't buying the entire business, but (say) half of it? What's changed? (This is roughly what is being proposed here)