Looks like AS has plenty of time to figure it out, as it's possible WN won't even sell a ticket until early 2019, let alone begin service:
https://www.bizjournals.com/dallas/n...hts-up-in.html
Kelly said he’s hopeful that Southwest will be flying to Hawaii by the end of 2018, but if it’s not, he’s confident the airline will at least be selling tickets for flights that start in early 2019.