Avalanche 6 GA release date is still TBD, but we are getting very close. It is quite different then the Avalanche 4.x and 5.x versions. It requires MSSQL and there will not be SE and MC versions it will just be Avalanche. However if you select to install the Mobile Device Server with the default installation it will act similar to the previous SE versions.
It will be the first Avalanche version to have a native smart device support. Migrating up you will have to be on a 5.3.x version(SE or MC) prior to upgrading to 6. You can take a preview of the system requirements in the help documentation from here .
Regards,
Nick