I agree and most likely that is whats going to happen here. For me bitcoin can't survive by itself at this time without fiat conversion. Most btc transactions are still converted to fiat. People are so used and reliant to this main currency that it would take i think more than a few decades before bitcoin could even compete with fiat in supremacy. Though as you've said it would be very beneficial if it could be a secondary option much like how we use credit and debit cards today
I'm not sure of that
In fact, I'm very dubious that people would actually want to pay with bitcoins for their daily expenses unless they wanted to show off (which is not a good idea either). Folks may have to convert Bitcoin to fiat having "no other options to spend their money" if they literally had no other option, for example, if they had no fiat in their pockets. If you ask me, spending precious bitcoins on trivial things is a downright stupid idea since Bitcoin is a much better vehicle for speculation than fiat as well as a store of value