I've not seen this list of non-stop international cities announced officially until now. No mention of which destinations each city will get though. Per WN rep Nicole via Facebook:
Hi Athena - The following U.S. cities will have nonstop service and serve as gateway cities to international destinations: Atlanta, Austin, Baltimore/Washington, Chicago (Midway), Denver, Orange County/Santa Ana, Orlando, Milwaukee, and San Antonio. At this time we are limiting connecting service to international destinations as we roll out new international capabilities across our systems and network. We hope to fully convert the Southwest network to support connecting service to international destinations by the end of 2014, so stay tuned for updates. Thanks for reaching out! -Nicole