JBoss Fuse is labeled as an ESB, but in fact its based on Apache Karaf as the OSGi container. So you can run and deploy anything you want - just that its OSGi compliant.
Just use the minimal distribution of JBoss Fuse, to not include stuff you do not need installed out of the box. Otherwise you can customize what JBoss Fuse should included out of the box, in the etc configuration files.
Notice that Apache Karaf is by default using Apache Felix as the OSGi framework, and supporting Spring-DM 1.x and Apache Aries Blueprint as spring and blueprint.
Thanks for the reply, Claus.
So FUSE is an OSGI runtime with extended functionality. If we wanted to migrate, we would need to drop any "bits" of Wildfly we are using into the deploy directory (as bundles).
Yeah if you are using any of the Wildfly bits in your applications.
Some bits like JPA / Hibernate / Servlet / WS (using Apache CXF) et all is also available from JBoss Fuse / Apache Karaf. But things like EJB's is not.