Sorry if it wasn't clear. Yes, the hub to hub communication will stop. It is pretty much telling the hub MX that it shouldn't form a VPN tunnel with any other hubs. They won't share routes with each other because there is no tunnel. Having a tunnel sharing routes is what could cause problems if Hub A advertises a subnet that now all of a sudden gets advertised into Hub B. It sounds like there is some overlap which would cause some looping in your network where having Hub A routes getting advertised into OSPF in Hub B's data center would cause some problems. If the VPN tunnel isn't there then it wouldn't get advertised into OSPF. I've worked with lots of customers to disable hub to hub. They know they don't want them talking as both data centers share the same subnets, so disabling the hub tunnels will prevent them from causing routing loops. It would really depend on your setup. Testing in a lab organization would be your best way to see how it behaves.
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