Of course. Granted, the other real-world entities I imagine being upgraded to megacorp status are Google and Abercrombie+Finch (slightly less plausible now, but whatever) - trying to make a 'run' into a corp where the dress code also extends to include mandatory plastic surgery according to a corp template is a delightfully creepy image.
At this point, you don't need made-up MegaCorps for a Shadowrun game. Just use real life megacorps like McDonalds, Universal, Hasbro, FIFA, Malboro, Monsanto, FIFA, and Disney. Companies that can, and in some cases have, ruin a small or financially unstable country.