Is WildFly capable of handling 10000 request per 1/10 of a second? Now we are using OpenShifts platform
Even more, but all depends on hardware & network of the machine you are running one.
In some tests we got more than 5M req/sec one single server.
But it all depends on hardware, network and your code, if your code takes lots time to process requests that will be your bottleneck not the web servers.
As it goes for OpenShift I cannot comment as there are many flavors and different ways of deployment.
You have OpenShift online, which has many different tiers of performance (free, paid) or you go with OpenShift enterprise that you can deploy on your own hardware.