nginx does that already. The problem is it'll stop you being able to reload configuration on other bits of config. Once there's a config error nothing can reload.
Limited blast radius don't really apply when it comes to nginx config errors (which given its origins is understandable). One error in one bit of config and it all stops.
Just make sure consul-template never writes bad config as that will stop everything reloading. That's bit me a couple of times.