I'd be more worried about your TV. Heat is not good for televisions.
You have that right. My younger daughter, did that against my advice and the TV went up in smoke literally the first winter. A TV should never be hung above a working fireplace, and if you do the fireplace should never be in use when the TV is on.
The other problem with a TV over the fireplace, is that the TV is far too high. It is very uncomfortable. viewing and literally a pain in the neck.
Ceiling speakers are a bad idea, except for surround when there is no other option. You will need a ceiling center, now you have done it, otherwise you will localize to the center the whole time, and it will be stranger than it is already with voices from on high.
For other reading this thread, the most important thing about any device is its performance. That always has to come first. Then you work on form and function. You can't start the design of anything with form. Function always has to come at the start of any design process. If not, you are inclined to end up with gear and systems that have poor function.
