Depends what you understand by 'affected'.
Any villager you haven't traded with previously will become unemployed (losing current profession) directly after update - and then promptly find any unoccupied workstation and obtain a matching profession. (obvious exception: nitwits. Nitwits will be nitwits forever.)
Villagers you have traded with will keep their trades, even without workstations, or in presence of mismatching workstations. They still need their respective workstation type to reset most of their trades once you lock them through trading (currently (1.13.2-pre3) there's a bug that makes some pre-existing trades never to lock up) - but they won't change their professions normally. They will also be affected by their new workstations in that they will pathfind to them twice a day during 'work hours'.
Additionally, Rays Works found that through a very specific upgrade path you can earn your pre-existing "professionals" new 1.14-specific trades on top of the pre-existing ones through the new workstation. Details in the linked video.