Buy some ThinkPads or zBooks or Latitudes, give those to a subset of your affected users, then send the freed-up units to service. Repeat until all affected units have been serviced.
Then, when the time comes (soon?) to replace the 2015-2017 MBPs, consider whether you'd rather repeat that with future MBPs or buy something different that has on-site same-day service and user-replaceable batteries and other components.