We are talking about future proofing so let's make 1 BTC = $100,000 for easy math.
Suppose Joe blow wants to order a $5 cheeseburger in BTC. Here's a few different scenarios:
A. "That'll be 0.00005 BTC please."
B. "That'll be 0.05 mBTC please."
C. "That'll be 50 uBTC please."
D. "That'll be 50 bits please."
A and B are eliminated right off the bat because nobody wants to recall how many zeroes they've put after the decimal.
This leaves us with reasonable C and D, but the word "bit" is far more marketable than "micro-BTC". Micro-BTC just doesn't roll off the tongue like bits does.
For those who say we have MicroBitcoin already, it's not about us... we get it, we're fine. We're already invested into BTC. Get over yourself. It's about widespread adoption transcending mathematical literacy, and "bit" is the ideal solution concerning avoiding decimals as well as ownership psychology.
I'd also eliminate C. There's no one way to say it – it could be "yu bee tee cee", "myu bee tee cee", "yu bits", "myu bits" – and all are multisyllable mouthfuls. (Another alternative not shown, "mics", can need clarification that it's said "mikes" to avoid it being said like "micks", which can be read as a slur term for Irish.)
But there should also be an E, for the made-up synonym for µBTC 'zib', leaving the two options:
D. "That'll be 50 bits please."
E. "That'll be 50 zib please."
This is just as easy to say, has only one pronunciation, and avoids possible confusion from redefining 'bit'... which already has been used as an abbreviation for 'bitcoin', as in 'millibits', and has another important meaning as 'indivisible binary-digit' in the core crypto that generates/secures Bitcoin.
Zib also offers a better currency-character, 'Ƶ' (Z-with-stroke). Compare price labels:
ƀ50.00
(is that bitcoin or bits?)Ƶ50.00
Small units (millionths) are a great idea. But the name doesn't have to be overloaded 'bits'.