There will not be a Windows Home Server 2012 or a Windows Small business Server 2012 Standard (the one that comes with on premises Exchange Server).

http://www.zdnet.com/microsoft-goes-public-with-windows-server-2012-versions-licensing-7000000341/

We were looking at upgrading our SBS and moving Exchange to the cloud via SBS Essentials or a 3rd party Exchange host, but had some reservations about not having an on premises Exchange server. I guess our decision has now been narrowed.