Full circle?

The form cantabimus, ‘we will sing’  in Classical Latin later became cantare habemus. In modern Spanish, the corresponding form is cantaremos, a contraction of cantare habemus. In a way, we are now back where we started. The synthetic form turned into an analytic form, and this again turned into a synthetic form. The development does not stop here: Spanish has, besides the synthetic form, a new paraphrastic, i.e. analytic form,  vamos a cantar. Perhaps at some stage in the future, this will again turn into a synthetic form. It seems clear, anyway, that languages do not only lose morphology over time: they also develop it. (Hollmann, Willem B.: “Grammatical Change”, in: Culpeper, Jonathan, Katamba, Francis, et. al. (eds): English Language. Basingstoke: Palgrave Macmillan, 2009: 326-8)