The Chicago Cubs last year of contention? Nick Swisher is wrong on this. Kris Bryant, Javier Baez, Anthony Rizzo, and Willson Contreras are all signed until at least 2021. Jon Lester, Kyle Hendricks, and Yu Darvish, same thing.
In the minor leagues, there is Ian Happ, signed through 2023. The pieces for the Cubs are here, and still will be for a while. There is also a chance that the Cubs could sign some of these players to long term contracts, based on how the market is looking right now with the last two offseasons.