It'll take more that popular demand to get be to extend and potentially destroy my own work by dragging it on for too long.
If they pay me enough maybe? But even that's kinda iffy cause there's the possibility of me having to put in a LOT of work for something that could likely ruin the story / characters, especially if I really don't want it to go on.
Generally I think if I was in the situation were a series I have finished continues, it would NOT be because of reader demand, but because I thought of another story for these characters that I thought was good enough to warrant the work of creating a comic again.