i doubt it
if facebook adopt BTC, price will increase instantly

Just the day they will announce it, price will get 1.5 times at least. I think these companies can really benefit from this. All they need to do is to invest a lot of money at current prices and then make that announcement. It will pump the prices like hell and then they can sell all those bitcoins to make decent returns. If they see their platform being affected by the change, they can even take the decision back after they have sold all their initial investment.