The way I see it YARN is pushing Hadoop form being a distributed file system to a distributed OS. There are a lot of SOA-ish infrastructures that are being built or migrating to YARN (Storm, Samza) that are compelling servicehosts. You can also at weave from continuuity, that will help you host additional types of services.
to specifically address you q. - YARN is a good basis for SOA framework, it is more than a autoscaling it is a resource management and hosting framework and it is fast enough (esp. if you use one of the already developed infrastructures that are built on top of it)