New Windows Servers are like buses: None for ages, then two at once!

In-place upgrades arrive in Server 2019 and Semi-Annual, fonts sacrificed for containers

One of the previews is for the Windows Server vNext Long-Term Servicing Channel, aka Windows Server 2019. The other previews the Windows Server Semi-Annual Channel, the version that gets a release every six months but is only supported for 18 months."