ctive, this argument ignores the corollary that "[t]he potential for legal liability [under State law] `must be reasonable, not merely theoretical!" Legg l. Wyeth, 428 F.3d 1317, 1325 n.5 (11th Cir. 2005) (quoting Great Plains Trust Co.l. Morgan Stanley Dean Witter & Co., 313 F.3d 305, 312 (5th Cir. 2002)) (e