Releases have not stopped - all that has happened is that the project has been renamed to WildFly, since JBoss AS 7 we have releases for WildFly 8 and 9 and are currently working on WildFly 10.
'If they format their entire server, do they would be able to get binaries of JBoss 5 online? or they have to take a backup of it before formatting?'.
Jboss 5 binaries ware always available on sourceforge http://sourceforge.net/projects/jboss/files/JBoss/
and as long as sourceforge is online, binaries will stay there...
Also as Darran said, JBoss AS was renamed to WildFly after version 7 and first release under new name was 8.0.0.Final.
you can grab all WildFly releases from Downloads · WildFly
Thanks Toamz/Darren for your valuable information.