My very limited experience with your situation is that queen acceptance is
unlikely.

I had a hive earlier this spring which your description fit almost to a "T"
-  plenty of workers, deminishing brood, no eggs, lots of pollen coming in. I
tried 2 or three times to find the queen and could not. I assumed that
because I could find no eggs that no laying worker was present so I tried to
introduce a new queen. The 1st one was killed in her cage, the 2nd one I
confined to a push-in cage on empty comb for 5 days and she was also killed
on her release. End result is I depopulated the hive and installed a package.