I’ve connected with several mid-sized organizations in a similar situation. Most are considering a “hybrid” assessment approach. If the employee has already achieved goals or can reasonably impact the set goals prior to fiscal year-end (has ability to work and right tools / internal systems to achieve), then the standard assessment approach may suffice. If the employee is in a role where goal achievement is not possible, an assessment can be made on two factors: fiscal YTD contributions prior to the workforce disruption, and ability to engage/re-focus efforts for the final quarter based on changing business priorities.
This approach may have varying degrees of success, depending on your organization size and culture, and also how flexible the goal setting approach has been in the past. Those on quarterly goal plans have a natural opporutnity to asses and pivot, while those on annual goal plans are more focused on reaching a resolution that is viewed as "fair" by employees, with the ability to sustain motivation/engagement long term. The latter, may naturally result in less perfomrance differenciation than normal.