You have two options present when you confront Dance at the end of Blind Betrayal. You can either kill him or convice him and the brotherhood to let him live. What I would have liked is a 3rd option.

You convince Danse and Maxson (via Intelligence and Science skill checks) that he would be more valuable as a research subject as no other synth would willingly surrender to the brotherhood and be experimented upon. He is relocated to the The Prydwen and is disassembled for research. There you can have conversations with his disembodied head in a jar where you can have conversations with him. He will say things like "I really miss our adventures protecting the wasteland", "it really is a Honor to serve the brotherhood like no other could" or "It's not so bad a job, especially now that they've turned off my pain receptors."

After The Institute is defeated Maxson will inform you that "Danse was no longer necessary as a research subject now that The Institute has been eliminated." After giving you your Jet Pack he will also introduce you to their newest recruit. A robot cobbled together from power armor and a sentry bot that has had Danse's programming transferred into it. He's then is available as a companion (but can only be sent back to the brotherhood when he is no longer with you).

So, what do you think?

That sounds in line with the theme of the M. T. DLC in new vegas. though the sci-fi weirdness/comedy thing that worked for those in the big MT might not fit with the BoS, I can't see it as a thing that would fit them.

Conversing with his severred head, I dunno. Gen 3 synths are completely human, with the exception of the component in their brain. Decapitation is as fatal to gen 3s as they are to humans.

...however, if they were to upload that synth component into Brotherhood computers to try to figure out how they work, and they ended up uploading Danse's consciousness or something similar to it and had THAT converse with you...