In this simple example, you would have a single point of failure for the enterprise machines. But not any more than your enterprise's routers or Internet connection represent single points of failure.
However, you can have multiple gateways (and thus alternative routes). Furthermore, the IP address failover will instantly be noticeable to any other machine you have in the virtual network.
However, you can have multiple gateways (and thus alternative routes). Furthermore, the IP address failover will instantly be noticeable to any other machine you have in the virtual network.