They'll probably trademark the space bar, enter and backspace keys...and the delete key.
Oh, and by the way, it's
M$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
Stop posting.
Oh, and I'm still quite surprised people still think MS trademarked/patented/whatever the usage/keys/whatever of PgUp and PgDn. They patented the usage of a certain algorithm that references absolute document location and compares it against pixels, then moves the document exactly that much lower... or something. Anyway, it is something most programs never do.