I think not they cannot pr shpuld insay that they can never replace the dollars because the thing is the bitcoins are volatile and the dollars are not so the people wants to have a stable price they do not wanted to lose money but rather only to gain so the bitcoins doesn't go that way so they can never replace dollar. They might be used in day by day life but still they are just an alternative and besides the poor people cannot fully access bitcoins not unless the world will be a free wifi after all