This isn't about Activision's financials or viability. It's that Vivendi's losing money in other businesses and Activision isn't doing much for them so is a good candidate to sell.
I think they will just sell their stake (52% of ATVI shares) to the market , as it's unlikely any company has both the cash and the willingness to purchase them.
Microsoft wouldn't be a good fit because EA Sports has to produce games for all major platforms under contract.