For the flight today July 27, 2016 there are 13 First Class, and 91 Economy seats available. Not sure that is a very good load for a 767-4. While that is just a small example, do you have evidence for the load factors for that flight?
I take it you pulled the seat maps and counted the empty seats. It's not uncommon on longhaul flights for people (tour groups, etc.) to receive their seat assignment after they've checked in. Do not be deceived -- the LAX-DTW flight I was on last week showed 9 unassigned F and 133 Y seats but was actually oversold. An extreme example (hello, Economy Basic) yet but an example nonetheless.
That said, I would agree DL likely has too much capacity into MUC.
Assuming WN axed FNT because of the poor performance, DTW would gain more MDW, gain a seasonal TPA and RSW while maintaining a once weekly MCO flight. What can you see WN doing in this case? Full time TPA and RSW? Cut them and make room for daily MCO?
If WN whacked FNT (2-3 flights per day to MDW, seasonal weekly MCO), it's not going to have any impact on its DTW operations. In May, WN managed only a 56% LF at FNT.
And while the schedule has diversified -- gone are the dozen flights a day to MDW, replaced with service to PHX, LAS, BWI, etc. -- WN has been stagnant at DTW for over two decades. Recall when WN lead the expansion of Concourse A in the L.C. Smith Terminal, with plans to "double" service from DTW. The physical expansion of the terminal happened (WN was reimburse with PFC) but the service expansion never came.
WN briefly tried twice daily DTW/MCO nine years ago, during the height of the local downturn. The service was a colossal flop, the route was quickly dropped and became a $39 mainstain via DING for the remainder of its life. (And in spite of the $39 fares, loads were still terrible!) While airlines generally have short memories, WN doesn't seem to have forgotten about DTW/MCO -- subsequent seasonal service was heavily reduced and WN quickly dumped FL's twice-daily flights.
We don’t care what your next flight is.