We'll probably end up doing some magic with spacing and colors, it should be formatted like this to be easy for both btc and sat denomination:
12 345, 67 890 124 BTC
Discussion
8 decimal places is the weird thing.
However moving completely to sats will make things easy enough. 1BTC will be something like a Bell unit to dB (decibell), no one uses Bell as unit, because it is too inpractically big for most things.