If Bits were to be adopted then BTC & Satoshi would have to fad[e] away. You would then have kBits, MBits, GBits and so forth. SI prefixes go both directions.
Agree with BTC going away, also "Bitcoin" or "bitcoin" as a unit of measure would probably fade as price goes up. However "satoshi" could still remain in use in the same way "cents" are used today. Anyway, the full proposal is:
1 satoshi = smallest unit, pretty much in general use today
1 bit = 100 satoshi, eventually every day use, coffee, sandwiches, etc.
1 XBT = 1 bit, should be the official symbol on all exchanges, forex, etc.
1 BTC = 1000000 bits = kept for dealing with larger amounts, may fade
1 Bitcoin/bitcoin as a currency unit fades away
Bitcoin = the Bitcoin protocol
Notice that 1 microBitcoin = 100 satoshi = 1 bit = 1 XBT
When adopted we can all look forward to the day when a shave and a haircut will, once again, cost two bits.