Cordyline australis has been widely used outside in gardens here for about 20 years, and in the south, very successfully. However, the last two winters have seen the death of hundreds of them because they've been so harsh. If we continue to have those sorts of winters, then probably it'll be a plant we no longer use. If we return to the sorts of winters we've had for the previous ten to fifteen years, then they'll be fine. You don't say where you are in the country - obviously in the south and west, they're less likely to die. Note that the plain green leaved version is slightly hardier than those with red/purple leaves.
At the same time, they're not entirely suited to being indoors either, but there is a version for indoors - Dracaena marginata.