Mojang already has the smithing and fletching tables implemented. What we have in 1.14 is merely a placeholder for their "really cool idea" because they simply ran out of time in the 1.14 snapshot cycle (and also because they ARE workstations that villagers can claim). They're slated for the next major themed update, which will probably be 1.15 (I've heard talk that this was a confirmed no, however, with this version being a smaller cleanup cycle.)
I expect these two blocks will get the same treatment as the loom... all arrow recipes will be removed from the crafting table and added to the fletching table, all armor recipes will be removed from the crafting table and added to the smithing table, and they will each get a cool new GUI.
I also expect they'll add something extra to sweeten the change... much like how banner patterns don't get consumed.