You can repot them as nice little ponytail house plants, but they have a long way to go before you call them bonsai. However, that's not really accurate, as those plants don't 'do' traditional bonsai anyhow, just keeping them (but not yet!) in little pots and trimming the roots every year or two keeps them from growing larger, but that doesn't really make them 'bonsai' in the normal sense.