The Keystone XL permit was originally denied, then (illegally) approved by Executive Order. The nature of Executive Orders is that they can be, and frequently are, tossed out by the next guy in office. This isn't a big secret, so I don't have a ton of sympathy for anyone who "spent billions laying pipes" under a permit granted by EO. If they wanted a lower risk of losing everything, they should've waited for the standard permit process, instead of gambling on the EO and that Trump would win another term.