You're changing your tune, from
"It should not be worried about -- it's a non-issue because users would not notice if their clients were displaying nano-bitcoins",
to
"it should not be worried about now, because it will not matter for a long time."
I'm merely presenting two sides of the same coin and two reasons to not worry about something that is in no way an issue.
Well, if it will matter in a long time, then (1) it might be easier to address now, while bitcoin is young,
Nobody knows whether it will actually matter, maybe bitcoin will be used the same way as gold, to store value, maybe it will be used everyday by my girlfriend, maybe it will be used to back other currencies.
(2) if it is not addressed, it could harm acceptance, as some savier people will not adapt something in the short term that doesn't have a long term path to success,
What could really harm acceptance is a weak economy where it is hard to get a hold of real goods and service in exchange for your currency, no matter whether this currency is called "bitcoin", "bitcent", "nanocoin", or "john mac douglas the third".
and (3) you're still wrong that users would not notice whether their client displayed bitcoins or nano-bitcoins.
I never said users wouldn't notice, I said they wouldn't care, as long as they get to manipulate almost-integer values.
It's not how many bitcoins are issued that matters, it's whether it's possible to order 24/7 sushi with them that matters.
Educate yourself about the protocol, you'll discover that it's future-proof in lots of ways.
You're free to keep worrying, that would suck though, I don't like worrying.