I have the solution: Make wheelchairs "first on, last off". No exceptions.
Lead flight attendant should collect the connecting boarding pass/baggage claim check/ID of anyone wishing to use a wheelchair to pre-board LAST MINUTE. Establish a "wheelchair registry" as a part of the Delta profile of anyone who regularly/predictably needs one. Legal connection time for "registered" members goes up to >1 hour. This creates no conflict for "registered" connecting passengers having to deplane last & discourages people from having "miracle flights".
Alternative: A "red-flag" system for passengers who intermittently request a last-minute wheelchair for personal gain...much like what happens when you want to buy a last minute one-way international ticket with cash. (or pay for a ticket to a fraud plagued country with a credit card online.)
PPP