Can a carrier-sold Nexus 5 be reimaged to the default Google Nexus experience?
Unless the Google Play version is designed to work with Sprint's network, I don't think there is a process to do so.

However, there is good news.
First, Nexus devices (even from the carrier) tend to be mostly to entirely bloat free. For example, the Verizon Nexus 7 2013 is completely stock. Verizon loves to put bloat on their devices too...

Second, even if there is bloat on it, it should be very simple to root and remove the bloat. In the process, you'll have to wipe your data, so if you want to use that option, you'll want to do it right when you get the phone...