143k of those passengers were at Henley in Arden. Could a way be found for that station to stay open or not?
Yes, keep the line it's located on open.
From there to Bearley Junction is just over 4 miles, and that's all you'd be able to close for Henley in Arden to retain it's direct Birmingham service, doing so would of course sever the link to Stratford, fair to assume some of those 143k passengers are heading south. Worth noting that BR attempted to close this section of the route in the mid 80s (when passenger numbers nationally were at an all time low), it was rejected even then.
Another point against, I don't have copy of a pre-COVID-19 timetable to check but I would expect Stratford to Brum via Solihull to be a slower journey than via Shirley.