I would think Mary Louise Wilson is the front-runner.
And, massofmen. This has been discussed to death on threads. You cite Avenue Q winning which WAS unexpected, but what about these:
Millie winning over Urinetown
Spamalot winning over any of the other nominees
POTO over Into the Woods
The Lion King over Ragtime.
And all the movies you listed got reviews worse than Blonde's (with the exception of Hairspray, which got some great reviews)
and for some of them (DRS, Saturday Night Fever) they're older movies that aren't as popular today. Blonde is very recent and still popular with a teenage fanbase. I will do well.
I am a firm believer in serendipity- all the random pieces coming together in one wonderful moment, when suddenly you see what their purpose was all along.