There is no evidence of this and you are continually creating worst-case scenarios.
Please stop.
If the flu season is severe, then it could be quite catastrophic when combined with COVID-19. We should definitely be preparing for worst-case scenarios, and not downplaying potential severity because it's inconvenient.
Influenza: https://www.folkhalsomyndigheten.se/globalassets/statistik-u...
Calicivirus (Vinter vomiting disease): https://www.folkhalsomyndigheten.se/contentassets/0ad710ef37...
As said, this hinges on social distancing and hygiene measures being kept enforced. If you open a country fully again and get two simultaneous peaks then you are in for a bad time.
https://www.economist.com/graphic-detail/2020/09/12/the-sout...
I am not surprised that measures to avoid COVID-19 also reduces the spread of flu.