In the 2020's, can we go AT LEAST 1 DECADE without having a new Star Wars or Batman movie?

No that won't happen for just about anything now. They even reboot films that are only a couple of years old sometimes which is a joke. So you will get more Rocky (there already is a new Apollo film out), Rambo (being spoken about/made), Star Wars is dead for a while but give it time, Batman, Superman (also dead for now but...), Bourne, Bond, Nightmare on Elm street, Halloween  etc etc etc

In about 10 years or so expect them to start remaking the whole Avengers series again too.