At the timeframe discussed on the panel, I don't think Swift is really lagging. In few years, it has gone rather well, and in few more years, it should mature a lot more on multiple platforms. Right now, I think attempting to use Swift on a Linux server would be a big nuisance; it's enough to look at the open-source implementation of Foundation & co. and the many trivial things still missing. Once that is complete, it should start becoming more interesting. I don't think the push for Windows support will be very difficult.