I don't think its an good idea to have an bitcoin as a retirement account as the future of bitcoin is still blank. We don't know whether it will replace fiat or not but i would prefer to invest in some pension plans which would pay me assured amount of money monthly rather then going for bitcoin retirement account.
Nope, I guess you are wrong. For now of course it is still blank because we can't predict the future but why dont you start investing now to craft that future? Altough bitcoin can't replace the fiat we still can earning through it. For now 1 bitcoin is $200++ and may be in the future the value will increase again and it will be go higher too. If you going to invest now may be it is not too late but you dont want to invest its your choice