Confused by the single speed in title which generally means you only have one gear.
Provided it's the same 'speed' and the mech can cope with the cassette, yes.
^Just realised that, don't think the wheel hub will take a 12 speed cassette, so all in looking at £500+ to go from wired to wireless.....seems a bit over the top, but life is short....will sleep on it, and probably end buy buying a whole new back end of the bike!
Dont waste your money. Use it on something useful instead and go and test ride a wireless bike at an lbs.
Wireless is the height of luxury on a bike. Its great to hear the gears whirring away at the press of a button. But its not a necessity. A well tuned set of manual gears works just as well. I would rather spend the money on a good set of wheels.
My Di2 bike is my least used bike. The novelty soon wears off.
Just my opinion.