If you bought SBS with Software Assurance (SA) then all existing SBS licences will be upgraded to separate licences for Windows Server, Exchange and SQL Sever (for SBS Premium). You will face an increase in your ongoing SA costs (when your SA agreement comes up for renewal) because of this but you do have an upgrade path.
SBS won't disappear from retail until June 2013 and from OEMs until December 2013. You will still be able to buy SBS 2011 until those dates and, if you buy it with SA, get the upgrade to the separate 2012/2013 full products whenever you want.
If you didn't/don't buy SA then you will have to make alternative arrangements.
To people who are asking "what's wrong with the cloud?" the answers are bandwidth and security. Lots of places can't get the connectivity at reasonable price to make a cloud solution viable. Lots of people would rather their data stayed under their control, on their machines, on their premises.