Simples!
They need about 500 pilots to fly the Dragon routes in the narrowbody and avoid rostering over the monthly block hours number that is included in basic pay.
So, 500 retrained onto A320/1/neo, starting with the Training Ban breaking hero trainers.
The other 500 are terminated from COS18 with no LIFO/seniority early next year after the 2021 First Quarter review that reveals the already stated maximum of 25% of normal schedules to be flown due to continuing effects of COVID.