Currently, snapshots of
master are produced for Ubuntu 14.04, 16.04 and 18.04 - the three current LTS versions of Ubuntu. End-of-life for Ubuntu 14.04 is scheduled for April 2019.
Although to my knowledge there has not been a public announcement of Swift 5's planned release date, historically Swift has released in March (Swift 2.2 was March 2016 and Swift 3.1 was March 2017).
If Swift 5 is released around March 2019 that would be only a month before the end-of-life of Ubuntu 14.04. I don't believe it would be worth releasing an Ubuntu 14.04 package in that case.
Proposal: we should stop building
master on Ubuntu 14.04 now, do not release any
swift-5.0 convergence snapshots for Ubuntu 14.04, and do not release Swift 5 for Ubuntu 14.04.