Productivity will recover when businesses can use resources productively. It's either keep the scheme running until quarantine measures are reduced enough to allow businesses to start ramping back up and productivity increases again, or remove the scheme and push people to unemployment which is worse for productivity. If the government is daft enough to stop the scheme before the quarantine measures are reduced we're in for a shit-show of a decade.
(If morbidly curious, you can keep an eye on tribunal outcomes at https://www.gov.uk/employment-tribunal-decisions .. I just checked this month's unfair dismissal outcomes and not a single one was in the complainant's favour, though some may have been withdrawn due to negotiating an offer.)