It will depend on the flu strain and compatability of the vaccine to some extent which under normal circumstances is the greatest variable.
Plus weather. There were 50,000 excess deaths in 2018 between a virulent strain that was not anticipated in the vaccine development and a long hard ending to the winter with the Beast from the East, and spring not arriving until May.
But yes, I would expect Covid measures to also mitigate the spread of flu, particularly hitting Christmas socialising through the general population and passing in to more vulnerable people.
There is a significant overlap between those most suceptible to Covid and flu and you can't die seperately from both on different occasions. There will always be a section of the population at very high suceptibility of dying from the next upleasant infection that they get, flu, norovirus, now Covid 19 in the mix. Covid 19 death rates in the spring will have been augmented by a "good" flu winter survived by a greater than average number of very vulnerable people.
I would expect flu and Covid 19 deaths to be "shared" between both illnesses this year. Surplus deaths may be high over the winter, but I suspect that from experience this summer, that will be counter-balanced again next summer.
With an average age of death being 82, typically a very significant proportion of that population has "prematurely" lost months of life rather than years.