More just wondering if this could be done or if there have been reports of having it done. At the end of treatment with fixed braces, keep the brackets and wires intact to create a type of retainer. The wires would not pull or push, nor would elastics or headgear be necessary. Just brackets with fixed, zero-force wire. The idea would be to wear the 'retainer braces' about a year or 2 post active treatment vs a traditional retainer. The compliance would be built in, (can't take off braces like a retainer), if the teeth shifted, then an active wire would be tied in. Downsides might be in keeping the braces clean for that much longer. Has this been done?

Of course! 
The only true retainer are built-in fixed braces! And I think, headgear should be worn!