quantize 16-bit PNG or TIFF to 10-bit, 12-bit, or 14-bit PNG to save space on an IS?

[Lynx_TWO]

I had an idea the other day&*8230;

So, let's say we have all these 16-bit TIFFs for an Image / Frame Sequence, but we know that this is the final master, color grading is done, and so anything over 10, 12, or 14 bits will be a waste of space, right? So why not have an option to quantize those final 16-bit-per channel (48-bit RGB) mastered images to 10-bit (30-bit RGB, 1024 levels per channel), 12-bit (36-bit RGB, 4096 levels per channel), or 14-bit (42-bit RGB, 16384&*8236; levels per channel) before converting to 16-bit PNG? That way the color quantize is already done, we get to store a lossless backup in the smallest space possible since PNG will only store the actual bit depth in a 16-bit PNG image (or at least from my tests in Photoshop that is indeed what seems to happen), and when newer video compression schemes come out you have a lossless-but-highly-compressed source.

I used ximagic on a TIFF file from an image sequence, used kMeans quantization to 8-bit (24-bit RGB, 256 levels per channel), 10-bit (30-bit RGB, 1024 levels per channel), and 12-bit (36-bit RGB, 4096 levels per channel)

kMeans for Color Quantization: https://lmcaraig.com/color-quantization-using-k-means

Results with file size are shown below. I used LZW compression on the TIFF files and Mixed Prediction Method on the PNG files.
Per one frame

Filetype	8-bit result (KB)	10-bit result (KB)	12-bit result (KB)	16-bit result (KB)
TIFF [1080p]	2,533	3,807	4,556	10,613
PNG [1080p]	2,202	3,002	3,352	8,166
TIFF [2160p]	8,431	13,301	16,388	45,853
PNG [2160p]	4,519	7,344	9,014	27,550

Based on size differences and current folder of Frame Sequence Images

Sequence Type	8-bit archive (TB)	10-bit archive (TB)	12-bit archive (TB)	16-bit archive (TB)
TIFF - HD	0.34	0.52	0.62	1.44
PNG - HD	0.3	0.41	0.46	1.11
TIFF - HD @ 60fps	0.86	1.29	1.55	3.61
PNG - HD @ 60fps	0.75	1.02	1.14	2.78
TIFF - 4K	1.15	1.81	2.23	6.23
PNG - 4K	0.62	1	1.23	3.74
TIFF - 4K @ 60fps	2.86	4.52	5.57	15.58
PNG - 4K @ 60fps	1.53	2.5	3.06	9.36

Per average of the total folder size of all rendered frames. For 12-bit video you are talking cutting your archive of the original frames by 2/3

Is this a solid idea or am I way off base?

P.S. Image converter does not seem to be optimized to handle large sets of images such as these. When I clicked on the folder to select all the images, dBpoweramp Image Converter starting using the hard drive for about 5 hours before I finally ended the process and split things up into smaller batches