Site closure is for sure after the merger. I would nominate Pfizer St Louis and La Jolla on the top of my list.
The only thing left in Pfizer St Louis is Biopharm science, which survived because of the pilot plant there. Moreover, the lease with Monsanto will end in five years. Medimmune has all the capacity Pfizer St Louis can offer. So it might be the site of the highest risk of being shutdown.
Pfizer La Jolla: high risk of closure as speculated in recent news.