The biggest problem at the moment is social care, home care etc. Many people working in this field are from overseas, on low pay and often with no good contract, which means they could all get sent home at any moment.
https://qz.com/1804756/uk-social-care-sector-hit-hard-by-new-immigration-plan/
Maybe all the out of work factory and warehouse workers will be able to retrain as social care professionals. I mean, if you can drive a fork lift and stack a shelf, surely you can look after somebody with dementia or COPD?