I have to admit, when it comes to the Superman department in the "Arrowverse", we have definitely a come a LONG way since the beginning of this show.
3-4 years ago, we never thought that we would ever see Superman show up as a real character on this show and that his presence would only be felt via text messages or CGI body doubles.
Then when it was first announced that he would be making his first real appearance in the second season, we could never even imagine that he would be given a chance to interact with the other prominent heroes in the "Arrowverse".
Now look at where we are now. After a few years of waiting, we will finally get to see him not only interact with the likes of Green Arrow and The Flash, but fight alongside them as well.
So when it comes to the possibility of seeing him in his own show, I'm not ruling out anything anymore.