EAP 7.4 uses Undertow 2.2.x. Since UNDERTOW-1684, Undertow does not support OSGi at all.
Fuse-Karaf flavor of Fuse 7 product is OSGi based platform and proper OSGi bundle manifests are crucial to it's operation.

Whether or not Fuse 7.9 will align to EAP 7.4, Fuse-Karaf part of entire product should continue to use supported version of Undertow 2.0.x.

It'd be no problem for me to bring back OSGi support to Undertow 2.1+ - especially because I see no linked document that'd justify such removal.
I have no problems with WFLY-1638 which concerns "JBoss OSGi" in general, but Undertow component itself being used not only in EAP/Wildfly should keep OSGi support - especially because Fuse 7 made such critical decision to switch from Jetty to Undertow.

/cc: acunning@redhat.com, janstey@redhat.com, gmalinko, drieden@redhat.com, garygaughan, yfang@redhat.com.