In 20 years, I can see two possible outcome for my comic.
The first being the popularity success of the project after I completed the series and its' sister story (which I hope would be more popular than the main series). This outcome is a slim chance but it's possible.
Second outcome would be my comic not gaining any popularity due to the massive sea of other comics, hence when it completes it dies. I do think I can redirect people to read my old work if they are curious about the other stories that I have to tell, it's risky but possible.
Despite the two possible outcome there is a third one that I feel might be something many people consider a bad omen and that is me going to other worlds before I could finish tying the story into a bow. It's something I think about every now and again which is why I think it's important to keep my stories in documents in case anything like that happens. Like, you never know, not everyone lives long enough to tell their tale.